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-version 1.33, 2025/04/20 15:43:32
+version 1.59, 2025/05/18 20:40:35
  Line 4
  @settitle The FreeM Manual
  @copying
- This manual is for FreeM, (version 0.64.0-rc1), which is a free and open-source implementation of the M programming language.
+ This manual is for FreeM, (version 0.65.1-rc0), which is a free software implementation of the M programming language.
+ Print-optimized versions of this book are typeset in @emph{Computer Modern} by the author using the @emph{GNU Texinfo} tools.
  Copyright @copyright{} 2014-2025 Coherent Logic Development LLC
- Line 18  Permission is granted to copy, distribut
+ Line 19  Permission is granted to copy, distribut
  @title The FreeM Manual
  @subtitle @sc{The Official Manual of FreeM}
- @subtitle Version 0.64.0-rc1
+ @subtitle Version 0.65.1-rc0
  @c@vskip 10pt
  @c@center @image{freem-logo-sm,,,,.png}
  @author Serena Willis
- Line 42  This is the official manual for the Free
+ Line 43  This is the official manual for the Free
  @menu
  * Introduction::                        About the FreeM Project, its history, and its goals.
+ * Document Conventions::                Conventions used in this manual.
+ * A Note on Standards::                 FreeM positioning regarding the M Development Committee.
  * FreeM Invocation::                    How to invoke FreeM from the command line.
  * The FreeM Environment Daemon::        Managing shared resources in the FreeM environment.
  * The FreeM Direct-Mode Environment::   Executing M programs interactively.
+ * Debugging::                           The program development cycle of FreeM.
+ * Program Development Cycle::           How to create, edit, test, and run FreeM programs.
  * Directives::                          Per-Routine Language Directives.
  * Intrinsic Special Variables::         Intrinsic Special Variables.
- Line 91  This is the official manual for the Free
+ Line 96  This is the official manual for the Free
  * Interrupt Handling::                  How FreeM handles interrupts.
  * Error Processing::                    How to handle errors in M program code.
  * FreeM Error Codes::                   Explanations of each FreeM error code.
- * Debugging::                           The program development cycle of FreeM.
  * System Configuration::                Configuring your FreeM installation.
  * Accessing FreeM from C Programs::     How to use the mlib interface.
  * FreeM Administrator::                 The fmadm system manager tool.
- * FreeM Legacy Utilities::              FreeM legacy system manager utilities.
  * FreeM VIEW Commands and Functions::   Getting and setting info about FreeM internals.
  * Implementation Limits::               FreeM limitations.
  * US-ASCII Character Set::              The US-ASCII character set.
- Line 109  This is the official manual for the Free
+ Line 112  This is the official manual for the Free
  @node Introduction
  @unnumbered Introduction
- FreeM started its life as @emph{FreeMUMPS}, written for MS-DOS and ported to SCO UNIX by a mysterious individual going by the name of "Shalom ha-Ashkenaz". It was released to MUG Deutschland in 1998. In 1999, Ronald L. Fox ported FreeM to the Red Hat Linux 5 of the GNU/Linux operating system. Thereafter, maintenance was taken over by the Generic Universal M Project, which changed its name first to Public Standard MUMPS and then by popular request to FreeM.
+ FreeM started its life as @emph{FreeMUMPS}, written for MS-DOS and ported to SCO UNIX by a mysterious individual going by the name of "Shalom ha-Ashkenaz". It was released to MUG Deutschland in 1998. In 1999, Ronald L. Fox ported FreeM to the Red Hat Linux 5 distribution of the GNU/Linux operating system. Thereafter, maintenance was taken over by the Generic Universal M Project, which changed its name first to Public Standard MUMPS and then by popular request to FreeM.
  When GT.M was open-sourced in late 1999, FreeM and GUMP were essentially abandoned. L.D. Landis, the owner of the original GUMP SourceForge project, and one of FreeM's significant contributors, passed maintenance of FreeM and ownership of its SourceForge project to Serena Willis in 2014. At this point, FreeM would not compile or run on modern Linux systems, so steps were taken to remedy the most pressing issues in the codebase. Limitations on the terminal size (previously hard-coded to 80x25) were lifted, and new @code{$VIEW} functions were added to retrieve the terminal size information. @code{$X} and @code{$Y} intrinsic special variables were updated to support arbitrary terminal sizes, and FreeM was once again able to build and run.
- In February of 2020, work began in earnest to build a development and support infrastructure for FreeM and begin the careful process of refining it into a more stable and robust product.
+ In February of 2020, work began in earnest to build a development and support infrastructure for FreeM and begin the careful process of refining it into a more stable and robust application.
+ For more information on FreeM history, see @code{@emph{$PREFIX}/share/freem/doc/freem_history.*} (distributed in PostScript, PDF, and plain text formats).
  @section Production Readiness
- Line 144  Current contributors denoted with a @emp
+ Line 149  Current contributors denoted with a @emp
  @cindex contributors, Gerum, Winfried
  @cindex contributors, Kreis, Greg
  @cindex contributors, Landis, Larry
+ @cindex contributors, McGlothlen, Ken
  @cindex contributors, Milligan, Lloyd
  @cindex contributors, Morris, Steve
  @cindex contributors, Murray, John
- Line 185  Larry Landis (Coordination, Code, Docume
+ Line 191  Larry Landis (Coordination, Code, Docume
  Rick Marshall (Testing, MDC Conformance) @emph{+}
  @item
+ Ken McGlothlen (Apple Silicon build/test environment, proofreading of documentation) @emph{+}
+ @item
  Lloyd Milligan (Code, Testing, Documentation)
  @item
- Line 224  Serena Willis (Current Maintainer and Pr
+ Line 233  Serena Willis (Current Maintainer and Pr
  Steve Zeck (Code)
  @end itemize
+ @node Document Conventions
+ @chapter Document Conventions
+ @cindex document conventions
+ @cindex conventions
+ @section Formatting Conventions
+ This manual uses the following formatting conventions:
+ @itemize
+ @item Code examples, filesystem paths, and commands are presented in @code{monospace}
+ @item Placeholders where the reader is expected to supply a replacement value are presented in @code{@emph{monospace italics}}, and depending on context, may be surrounded by angle brackets
+ @item New terminology is introduced in @emph{proportional italics}
+ @end itemize
+ @section Definitions
+ FreeM uses abbreviations for common language elements:
+ @table @asis
+ @item @emph{$PREFIX}
+ Refers to the base filesystem location within which FreeM is installed. For most distribution methods of FreeM, @emph{$PREFIX} represents either @code{/} or @code{/usr/local}.
+ @item @emph{dlabel}
+ Refers to a label in an M routine, beginning in the first column of the line. Can be a @emph{name} or an @emph{intlit}.
+ @item @emph{entryref}
+ Refers to an M routine entry point, denoted in the format @code{@emph{dlabel} [+@emph{intexpr}][^@emph{routine}]}.
+ @item @emph{expr}
+ Refers to any expression. Often presented in the format @emph{expr V <type>}, where @emph{V} means @emph{giving}; e.g., @emph{expr V lvn} means @emph{expression giving local variable name}.
+ @item @emph{glvn}
+ Refers to the name of an M global, local, or structured system variable.
+ @item @emph{gvn}
+ Refers to the name of an M global variable.
+ @item @emph{intexpr}
+ Refers to an integer expression.
+ @item @emph{intlit}
+ Refers to an integer literal.
+ @item @emph{ISV}, @emph{isv}
+ Refers to an M intrinsic special variable; @code{$JOB} and @code{$IO} are examples of ISVs.
+ @item @emph{L}
+ Indicates a @emph{list} of the following item, e.g., @emph{L gvn} means @emph{list of global variable names}.
+ @item @emph{lvn}
+ Refers to the name of an M local variable.
+ @item @emph{postcondition}
+ A @emph{tvexpr} immediately following a command verb affecting that command's execution.
+ @item @emph{strlit}
+ Refers to an M string literal.
+ @item @emph{ssvn}
+ Refers to the name of an M structured system variable.
+ @item @emph{tvexpr}
+ Refers to a truth-valued expression, i.e., an expression interpreted as a truth value.
+ @end table
+ @node A Note on Standards
+ @chapter A Note on Standards
+ @cindex MDC
+ @cindex M Development Committee
+ @cindex ANSI X11.1
+ @cindex standards, ANSI
+ @cindex standards, MDC
+ FreeM attempts to implement as many features as possible from the M Development Committee's unpublished @emph{Millennium Draft Standard}, as well as its predecessors.
+ The maintainer of FreeM (who is also the author of this book) is largely in favor of standardization efforts, and hopes that the MDC will resume activities, and will happily participate if it does so in an open, public, transparent, and democratic manner. Until then, however, FreeM will attempt to improve the M language, in cooperation with other free software M implementers where possible. Any breaking changes introduced in future MDC releases of the @emph{Standard} (such as the rumored @emph{M5}) which prove incompatible with FreeM will be handled via the @code{$DIALECT} special variable (to be changed to @code{$ZDIALECT} in a coming release).
+ The conformance document required per the @emph{Standard} should be installed as a @code{man} page on any computer system where FreeM is made available. Simply type @code{man freem_conformance} to access.
  @node FreeM Invocation
  @chapter FreeM Invocation
  @cindex invocation, command-line
- Line 240  When @code{-r} or @code{--routine} are p
+ Line 315  When @code{-r} or @code{--routine} are p
  @section %SYSINIT Routine
- The @code{%SYSINIT} routine runs every time a FreeM interpreter process starts. This routine defines some useful constants, enables handling of @code{TRIGGER} events, and handles the execution of code passed via the @code{-x\--execute} or routines passed via @code{-r|--routine}.
+ The @code{%SYSINIT} routine runs every time a FreeM interpreter process starts. This routine defines some useful constants, enables handling of @code{TRIGGER} events, and handles the execution of code passed via the @code{-x|--execute} or routines passed via @code{-r|--routine}.
  Do not modify the supplied @code{%SYSINIT} routine to add site-specific startup items. Instead, create a @code{LCLINIT} routine in the @code{USER} namespace of one or more environments. @code{%SYSINIT} will automatically run @code{LCLINIT} each time it starts.
- Line 355  If the daemon is started with @option{--
+ Line 430  If the daemon is started with @option{--
  The @option{--environment} option will start the daemon for the specified @emph{environment-name}. The default environment, if unspecified, is called @code{DEFAULT}. If using an environment other than @code{DEFAULT}, interpreter processes that wish to also connect to the same environment must also use the @option{--environment} option when starting, and @code{libfreem} clients must also pass the environment name as the first argument to the @code{freem_init()} function. Environments allow you to run multiple, isolated instances of FreeM on the same machine, whose globals and routines are distinct and unique.
- The @option{--shmsize} option specifies the size in bytes of the FreeM shared memory segment. The default is 4194304 bytes. Increasing the size of the FreeM shared memory segment will, at the cost of increased memory usage, increase the number of concurrent jobs and lock table entries available to the environment; decreasing the size of the segment will have the expected opposite effect. Note that you must also pass @option{--shmsize} with the same number of bytes to any interpreter process to be used with an environment whose daemon uses a non-default shared memory segment size.
+ The @option{--shmsize} option specifies the size in bytes of the FreeM shared memory segment. The default is 16,777,216 bytes (16 megabytes). Increasing the size of the FreeM shared memory segment will, at the cost of increased memory usage, increase the number of concurrent jobs and lock table entries available to the environment; decreasing the size of the segment will have the expected opposite effect. Note that you must also pass @option{--shmsize} with the same number of bytes to any interpreter process to be used with an environment whose daemon uses a non-default shared memory segment size.
  Attempting to start a FreeM interpreter process without a daemon running with the same environment name will result in an error.
- Line 370  Attempting to start a FreeM interpreter
+ Line 445  Attempting to start a FreeM interpreter
  The FreeM direct-mode environment is the mode entered when FreeM is invoked without the use of @option{-r @emph{<entryref>}} or @option{--routine=@emph{<entryref>}}:
  @example
- Coherent Logic Development FreeM version 0.64.0-rc1 (x86_64-pc-linux-gnu)
+ Coherent Logic Development FreeM version 0.65.1-rc0 (x86_64-pc-linux-gnu)
  Copyright (C) 2014, 2020, 2021 Coherent Logic Development LLC
- Line 522  DEFAULT.USER>
+ Line 597  DEFAULT.USER>
  Such expressions will be immediately evaluated, and the result printed on @code{@ref{$IO}}.
+ @node Debugging
+ @chapter Debugging
+ @cindex debugging
+ @section Debugging Synopsis
+ FreeM includes an interactive debugger, entered using the @code{BREAK "DEBUG"} command. The debugger is also entered if @code{Ctrl-C} is pressed, @code{Ctrl-C} handling is enabled, and you are in direct mode.
+ If you would like to enter the debugger automatically each time an error is encountered, add the following to your @code{LCLINIT} routine:
+ @example
+ S $ETRAP="B ""DEBUG"""
+ @end example
+ @section Debugging Commands
+ The debugger uses its own unique command language, where M commands are unavailable. Commands are as follows:
+ @table @asis
+ @item @code{exit}, @code{quit}
+ Exits the debugger and returns to direct mode or normal program execution.
+ @item @code{e} @emph{glvn}, @code{examine} @emph{glvn}
+ Prints the value of @emph{glvn} to the terminal.
+ @item @code{t}, @code{trace}
+ Toggles @emph{trace mode} on and off. When trace mode is on, FreeM will display information about each @code{DO} or @code{GOTO} command encountered, including the routine which invoked the branch, which type of branch was invoked, and the target of the branch.
+ @item @code{s}, @code{step}
+ Single-steps through FreeM code command-by-command.
+ @item @code{n}, @code{next}
+ Single-steps through FreeM code line-by-line.
+ @item @code{c}, @code{cont}, @code{continue}
+ Resumes normal program execution, disabling single-step mode.
+ @item @code{bt}, @code{backtrace}
+ Produces a stack trace.
+ @item @code{h}, @code{halt}
+ Halts the process being debugged and returns control to the operating system.
+ @item @code{w [[+|-|?]@emph{<glvn>}]}, @code{watch [[+|-|?]@emph{<glvn>}]}
+ With no arguments, toggles watchpoints on and off. With @code{+}, adds @emph{<glvn>} to the watchlist. With @code{-}, removes @emph{<glvn>} from the watchlist. With @code{?}, queries the watch status of @emph{<glvn>}.
+ @end table
+ @node Program Development Cycle
+ @chapter Program Development Cycle
+ @cindex program development
+ This chapter covers the essential activities of program development in the FreeM environment, including viewing, creating, editing, and running routines.
  @node Directives
  @chapter Directives
  @cindex directives
- Line 592  Please note that FreeM is not entirely s
+ Line 710  Please note that FreeM is not entirely s
  * $SYSTEM::                  MDC system ID of FreeM.
  * $TEST::                    Truth value of last conditional expression or result of certain @code{LOCK} operations.
  * $TLEVEL::                  Current level of transaction nesting.
- * $WITH::                    Current variable prefix set by @code{WITH} command.
+ * $WITH::                    Current variable prefix set by @code{ZWITH} command.
  * $X::                       Current horizontal screen position.
  * $Y::                       Current vertical screen position.
  * $ZA::                      Current position of file on @code{$IO}.
- Line 788  uncommitted transactions exist.
+ Line 906  uncommitted transactions exist.
  @cindex $WITH
  @cindex intrinsic special variables, $WITH
- Returns the variable prefix set by the @code{@ref{WITH}} command.
+ Returns the variable prefix set by the @code{@ref{ZWITH}} command.
  @node $X
  @section $X
- Line 1007  See @emph{https://wiki.osdev.org/Target_
+ Line 1125  See @emph{https://wiki.osdev.org/Target_
  * $ZLSD()::                             Compute Levenshtein distance between two arguments.
  * $ZM()::                               Unknown.
  * $ZNAME()::                            Unknown.
- * $ZNEXT()::                            Unknown.
+ * $ZNEXT()::                            Return glvn of next numeric subscript following given glvn.
  * $ZORDER()::                           Unknown.
  * $ZPIECE()::                           Unknown.
  * $ZPREVIOUS()::                        Unknown.
- Line 1205  The optional second argument indicates t
+ Line 1323  The optional second argument indicates t
  @cindex intrinsic functions, $NEXT
  Deprecated. Use @code{$ORDER} instead.
+ Returns the next numeric subscript of the specified glvn.
+ @emph{Syntax}
+ @example
+ $NEXT(@emph{glvn})
+ @end example
+ @emph{Example}
+ Assume the following array:
+ @example
+ ^foo(1)=""
+ ^foo(2)=""
+ @end example
+ And the following code:
+ @example
+  W $ZNEXT(^foo(1)) ; => 2
+ @end example
  @node $ORDER()
  @section $ORDER
- Line 1605  Returns the Levenshtein distance between
+ Line 1745  Returns the Levenshtein distance between
  @cindex intrinsic functions, $ZM
  @cindex intrinsic functions, implementation-specific
+ Purpose unknown.
  @node $ZNAME()
  @section $ZNAME
  @cindex $ZNAME
- Line 1613  Returns the Levenshtein distance between
+ Line 1755  Returns the Levenshtein distance between
  Purpose unknown.
+ This function relies on the value of @code{$VIEW(71)} being @code{0} (this is not the default).
  @node $ZNEXT()
  @section $ZNEXT
  @cindex $ZNEXT
  @cindex intrinsic functions, $ZNEXT
  @cindex intrinsic functions, implementation-specific
- Purpose unknown.
+ Returns a fully-formed variable reference of the next numeric subscript of the specified glvn.
+ @emph{Syntax}
+ @example
+ $ZNEXT(@emph{glvn})
+ @end example
+ @emph{Example}
+ Assume the following array:
+ @example
+ ^foo(1)=""
+ ^foo(2)=""
+ @end example
+ And the following code:
+ @example
+  W $ZNEXT(^foo(1)) ; => ^foo(2)
+ @end example
+ This function relies on the value of @code{$VIEW(71)} being @code{1} (this is the default).
  @node $ZORDER()
  @section $ZORDER
- Line 1905  Identical to @ref{$TRANSLATE()}, except
+ Line 2072  Identical to @ref{$TRANSLATE()}, except
  * !::                                   Run an external program or command.
  * !!::                                  Launch a subshell from FreeM direct mode.
  * ABLOCK::                              Increment the block counter for one or more event classes.
- * ASSERT::                              Raise error when a conditional expression evaluates @emph{false}.
  * ASTART::                              Enable asynchronous event handling for one or more event classes.
  * ASTOP::                               Disable asynchronous event handling for one or more event classes.
  * AUNBLOCK::                            Decrement the block counter for one or more event classes.
  * BREAK::                               Interrupt a running routine to allow interactive debugging.
  * CLOSE::                               Close an input/output device.
- * CONST::                               Define a constant that cannot be altered after initial definition.
  * DO::                                  Transfer program control to one or more subroutines or introduces a new execution level.
  * ELSE::                                Execute the remainder of a line if @code{@ref{$TEST}} evaluates @emph{false}.
  * FOR::                                 Repeat execution of a line or block of code.
- Line 1924  Identical to @ref{$TRANSLATE()}, except
+ Line 2089  Identical to @ref{$TRANSLATE()}, except
  * KSUBSCRIPTS::                         Kill only the descendant subscripts of a local, global, global, or structured system variable.
  * KVALUE::                              Kill only the value of a local, global, or structured system variable.
  * LOCK::                                Control advisory locking for concurrency control.
- * MAP::                                 Map a global name to a non-default namespace.
  * MERGE::                               Merge contents of one local, global, or structured system variable into another.
  * NEW::                                 Introduce a new scope for a specified local variable or intrinsic special variable or instantiate an object.
  * OPEN::                                Open a sequential or socket input/output device.
- Line 1933  Identical to @ref{$TRANSLATE()}, except
+ Line 2097  Identical to @ref{$TRANSLATE()}, except
  * SET::                                 Set the value of a local variable, global, intrinsic special variable, or structured system variable.
  * TCOMMIT::                             Commit a transaction.
  * THEN::                                Preserve @code{@ref{$TEST}} until the end of the current line.
- * THROW::                               Programmatically raise an error condition.
  * TROLLBACK::                           Roll back all pending transactions.
  * TSTART::                              Introduce a new transaction processing level.
- * UNMAP::                               Remove a mapping of a global to a non-default namespace.
  * USE::                                 Set the currently-active input/output device.
  * VIEW::                                Modify FreeM internal parameters.
- * WATCH::                               Enable or disable watchpoints, or set or clear watchpoints on specified globals, locals, or structured system variables.
- * WITH::                                Set prefix for future variable references.
  * WRITE::                               Write output to current input/output device.
  * XECUTE::                              Interpret string as M code.
- * ZBREAK::                              Unknown.
+ * ZASSERT::                             Raise error when a conditional expression evaluates @emph{false}.
- * ZGO::                                 Unknown.
+ * ZBREAK::                              Enable/disable ZBREAK mode.
- * ZHALT::                               Unknown.
+ * ZCONST::                              Define a constant that cannot be altered after initial definition.
+ * ZEDIT::                               Edit a routine using an external editor.
+ * ZGOTO::                               @code{GOTO} with @code{BREAK} control.
+ * ZHALT::                               Exit FreeM job with return value.
  * ZINSERT::                             Insert code into routine buffer.
- * ZJOB::                                Unknown.
+ * ZJOB::                                Invoke job, ignoring any timeouts.
  * ZLOAD::                               Load routine into routine buffer.
+ * ZMAP::                                Map a global name to a non-default namespace.
  * ZNEW::                                Unknown.
  * ZPRINT::                              Print contents of routine buffer.
- * ZQUIT::                               Unknown.
+ * ZQUIT::                               Quit multiple stack levels at once.
  * ZREMOVE::                             Remove code from routine buffer.
  * ZSAVE::                               Save routine buffer to disk.
- * ZTRAP::                               Unknown.
+ * ZTHROW::                              Programmatically raise an error condition.
+ * ZTRAP::                               Raise a FreeM error.
+ * ZUNMAP::                              Remove a mapping of a global to a non-default namespace.
+ * ZWATCH::                              Enable or disable watchpoints, or set or clear watchpoints on specified globals, locals, or structured system variables.
+ * ZWITH::                               Set prefix for future variable references.
  * ZWRITE::                              Write local variable, global, or structured system variable to @code{@ref{$IO}}.
  @end menu
- Line 2076  In its inclusive form, @code{ABLOCK} inc
+ Line 2244  In its inclusive form, @code{ABLOCK} inc
  In its exclusive form, @code{ABLOCK} increments the block counters for all event classes @emph{except for} those named in the list, provided the optional @emph{postcondition} is either @emph{true} or omitted.
- @node ASSERT
- @section ASSERT
- @cindex ASSERT
- @cindex commands, ASSERT
- @cindex commands, debugging
- @cindex commands, implementation-specific
- @cindex commands, non-standard
- @emph{FreeM Extension}
- Triggers error @code{ASSERT} if the supplied truth-valued expression @emph{tvexpr} is @emph{false} (@emph{1} is @emph{true}, and @emph{0} is @emph{false}), and that the optional @emph{postcondition} evaluates to @emph{true} or is omitted.
- The @code{ASSERT} error is catchable whether using standard-style, FreeM-style, or DSM 2.0-style error processing.
- @emph{Syntax}
- @example
-  ASSERT@emph{:postcondition} @emph{<tvexpr>}
- @end example
- @emph{Example}
- @example
- DEFAULT.USER> SET DEBUG=1
- DEFAULT.USER> ASSERT:DEBUG 1=1
- DEFAULT.USER> ASSERT:DEBUG 1=0
- >> Error ZASSERT:  programmer assertion failed in SYSTEM::^%SYSINIT  [$STACK = 0]
- >> ASSERT:DEBUG 1=0
-                    ^
- @end example
  @node ASTART
  @section ASTART
- Line 2215  In its argumentless form, @code{BREAK} s
+ Line 2348  In its argumentless form, @code{BREAK} s
  @emph{FreeM Extension}
- In its single-argument form, @code{BREAK} sets @emph{Ctrl-C} handling and error handling characteristics, provided the optional @emph{postcondition} is @emph{true} or omitted.
+ In its single-argument form, @code{BREAK} enters the interactive debugger or sets @emph{Ctrl-C} handling and error handling characteristics, provided the optional @emph{postcondition} is @emph{true} or omitted.
  The following table enumerates the possible values of @emph{breakflag}
  @table @code
+ @item "DEBUG"
+ Enters the interactive debugger
  @item 0
  Disables @emph{Ctrl-C} handling
  @item -2
- Line 2250  In its argumentless form, @code{CLOSE} c
+ Line 2385  In its argumentless form, @code{CLOSE} c
  In its single-argument form, @code{CLOSE} closes the I/O device associated with channel @emph{channel}, provided that @emph{channel} represents a currently-open device, and the optional @emph{postcondition} is @emph{true} or omitted.
- @node CONST
- @section CONST
- @cindex CONST
- @cindex commands, CONST
- @cindex commands, non-standard
- @emph{FreeM Extension}
- Defines a local @emph{constant}, or variable that cannot be altered after its initial definition, provided the optional @emph{postcondition} is @emph{true} or omitted.
- Constants must only be locals, and globals are not supported.
- @emph{Syntax}
- @example
- @code{CONST@emph{:postcondition} @emph{mref1}=@emph{initial-value1},...,@emph{mrefN}=@emph{initial-valueN}}
- @end example
  @node DO
  @section DO
  @cindex DO
- Line 2280  In its inclusive form, transfers program
+ Line 2398  In its inclusive form, transfers program
  DO[@emph{:postcondition}] @emph{entryref}[@emph{:postcondition}[,...]]
  @end example
+ @cartouche
+ @quotation
+ @emph{Non-Standard Behavior}
+ FreeM allows @code{DO} @emph{entryref}s to follow the format of @code{+@emph{intexpr}}. In this case, the value of @emph{intexpr} will be interpreted as an offset from the first line of the current routine.
+ @end quotation
+ @end cartouche
  In its argumentless form, transfers control to the following block of code where the line level is one greater than the level at which @code{DO} was encountered, provided the optional @emph{postcondition} evaluates to @emph{true} or is omitted.
  @emph{Syntax}
- Line 2305  ELSE[@emph{:postcondition}]
+ Line 2431  ELSE[@emph{:postcondition}]
  @quotation
  @emph{Non-Standard Behavior}
- FreeM allows a @emph{postcondition} on @code{ELSE}. While explicitly forbidden in the @emph{standard}--and for good reason--it was decided that FreeM should allow postconditions everywhere, both for the sake of foolish consistency (the likes of which Emerson warned against), and for the benefit of entrants to a hypothetical future obfuscated M contest, and those with a Machiavellian predisposition to wicked perversions and undue cleverness.
+ FreeM allows a @emph{postcondition} on @code{ELSE}. While explicitly forbidden in the @emph{Standard}, it was decided that FreeM should allow postconditions everywhere, both for the sake of foolish consistency (the likes of which Emerson warned against), and for the benefit of entrants to a hypothetical future obfuscated M contest, and those with a Machiavellian predisposition to wicked perversions and undue cleverness.
- Using postconditions on @code{ELSE} should be strictly avoided in production code, as they have no practical use, and may contribute to technical debt, hardening of the arteries, hobgoblins, a small mind, a surfeit of logic, climate change, Daily WTF rants, or meltdown of global financial markets.
+ Using postconditions on @code{ELSE} should be strictly avoided in production code, as they have no practical use, and may contribute to technical debt, hardening of the arteries, hobgoblins, a small mind, a surfeit of logic, climate change, @emph{Daily WTF} rants, or the meltdown of global financial markets.
  @end quotation
  @end cartouche
- Line 2403  Transfers program execution to another l
+ Line 2529  Transfers program execution to another l
  GOTO[@emph{:postcondition}] @emph{entryref}
  @end example
+ @cartouche
+ @quotation
+ @emph{Non-Standard Behavior}
+ FreeM allows @code{GOTO} @emph{entryref}s to follow the format of @code{+@emph{intexpr}}. In this case, the value of @emph{intexpr} will be interpreted as an offset from the first line of the current routine.
+ @end quotation
+ @end cartouche
  @node HALT
  @section HALT
  @cindex HALT
- Line 2451  IF[@emph{:postcondition}] @emph{tvexpr}[
+ Line 2586  IF[@emph{:postcondition}] @emph{tvexpr}[
  In its argumentless form, allows the remainder of the line of code following @code{IF} to execute only if @code{$TEST} evaluates to @emph{1}, provided the optional @emph{postcondition} evaluates to @emph{true} or is omitted.
  @emph{Syntax}
  @example
- IF[@emph{:postcondition}]
+ IF[@emph{:postcondition}]  @emph{command...}
  @end example
+ @cartouche
+ @quotation
+ @emph{Style Recommendation}
+ In the interest of readability and maintainability, we recommend avoiding the argumentless form of @code{IF} in new code. It is an obsolete relic of an era when routine sizes were severely limited, and can be difficult to spot, as the use of whitespace (@code{IF  @emph{command}}) makes the intent of its use non-obvious at a glance. It is also far too easy to inadvertently delete the extra space, leading to program errors easily avoided otherwise.
+ We recommend explicitly checking the value of @code{$TEST} instead, as in @code{IF $TEST @emph{command}} or @code{@emph{command}:$TEST ...}, as this makes the intent immediately clear both to M newcomers and seasoned experts, and sacrifices nothing of value, even on the oldest computer systems where FreeM can be used today.
+ @end quotation
+ @end cartouche
  @node JOB
  @section JOB
  @cindex JOB
- Line 2514  In the above @emph{inclusive} form, @cod
+ Line 2660  In the above @emph{inclusive} form, @cod
  @cartouche
  @quotation
  @emph{Note}
- The below @emph{argumentless} and @emph{exclusive} forms of @code{KSUBSCRIPTS} are not implemented in FreeM, as of version 0.64.0-rc1, but are planned for a future release.
+ The below @emph{argumentless} and @emph{exclusive} forms of @code{KSUBSCRIPTS} are not implemented in FreeM, as of version 0.65.1-rc0, but are planned for a future release.
  @end quotation
  @end cartouche
- Line 2549  In the above @emph{inclusive} form, @cod
+ Line 2695  In the above @emph{inclusive} form, @cod
  @cartouche
  @quotation
  @emph{Note}
- The below @emph{argumentless} and @emph{exclusive} forms of @code{KVALUE} are not implemented in FreeM, as of version 0.64.0-rc1, but are planned for a future release.
+ The below @emph{argumentless} and @emph{exclusive} forms of @code{KVALUE} are not implemented in FreeM, as of version 0.65.1-rc0, but are planned for a future release.
  @end quotation
  @end cartouche
- Line 2605  If @code{LOCK} succeeds within @emph{tim
+ Line 2751  If @code{LOCK} succeeds within @emph{tim
  LOCK[@emph{:postcondition}] @emph{name}[:@emph{timeout}][,...@emph{name}[:@emph{timeout}]]
  @end example
- @node MAP
- @section MAP
- @cindex MAP
- @cindex commands, MAP
- @cindex commands, implementation-specific
- @cindex commands, non-standard
- Maps global name @code{gvn} to be mapped to the non-default namespace @emph{expr V namespace}, provided the optional @emph{postcondition} evaluates to @emph{true} or is omitted.
- @emph{Syntax}
- @example
- MAP[@emph{:postcondition}] GLOBAL @emph{gvn}=@emph{expr V namespace}
- @end example
  @node MERGE
  @section MERGE
  @cindex MERGE
- Line 2869  Saves the value of @code{$TEST} until th
+ Line 3000  Saves the value of @code{$TEST} until th
  IF 1 THEN  WRITE "HELLO!",!
  @end example
- @node THROW
- @section THROW
- @cindex THROW
- @cindex commands, THROW
- @cindex commands, non-standard
- @emph{FreeM Extension}
- Raises an error condition as long as the optional @emph{postcondition} is @emph{true} or omitted.
- @emph{Syntax}
- @example
- @code{THROW@emph{:postcondition} @emph{expr V error-code}}
- @end example
- @emph{Example}
- @example
- @code{THROW "M102"}
- @end example
  @node TROLLBACK
  @section TROLLBACK
  @cindex TROLLBACK
- Line 2954  If you are using more than one transacti
+ Line 3064  If you are using more than one transacti
  TSTART (FOO,BAR):(SERIAL,TRANSACTIONID="FOO")
  @end example
- @node UNMAP
- @section UNMAP
- @cindex UNMAP
- @cindex commands, UNMAP
- @cindex commands, implementation-specific
- @cindex commands, non-standard
- Removes any mapping connecting @emph{gvn} to a non-default namespace, provided the optional @emph{postcondition} evaluates to @emph{true} or is omitted.
- @emph{Syntax}
- @example
- UNMAP GLOBAL @emph{gvn}
- @end example
  @node USE
  @section USE
- Line 3272  VIEW 133:@emph{tvexpr}
+ Line 3368  VIEW 133:@emph{tvexpr}
  @end table
- @node WATCH
- @section WATCH
- @cindex WATCH
+ @node WRITE
- @cindex commands, WATCH
+ @section WRITE
+ @cindex WRITE
+ @cindex commands, WRITE
+ @node XECUTE
+ @section XECUTE
+ @cindex XECUTE
+ @cindex commands, XECUTE
+ @node ZASSERT
+ @section ZASSERT
+ @cindex ZASSERT
+ @cindex commands, ZASSERT
  @cindex commands, debugging
  @cindex commands, implementation-specific
  @cindex commands, non-standard
  @emph{FreeM Extension}
- Sets a watchpoint on a global, local, or SSVN node.
+ Triggers error @code{ZASSERT} if the supplied truth-valued expression @emph{tvexpr} is @emph{false} (@emph{1} is @emph{true}, and @emph{0} is @emph{false}), and that the optional @emph{postcondition} evaluates to @emph{true} or is omitted.
- @emph{Syntax}
+ The @code{ZASSERT} error is catchable whether using standard-style, FreeM-style, or DSM 2.0-style error processing.
- In its @emph{argumentless} form, @code{WATCH} toggles watchpoints on and off, provided the optional @emph{postcondition} is @emph{true} or omitted.
+ @emph{Syntax}
  @example
- WATCH[@emph{:postcondition}]
+  ZASSERT@emph{:postcondition} @emph{<tvexpr>}
  @end example
- In its @emph{inclusive} form, @code{WATCH} adds, removes, or examines watchpoints, provided the optional @emph{postcondition} is @emph{true} or omitted.
+ @emph{Example}
- A @code{+} adds a new watchpoint to the following variable.
+ @example
+ DEFAULT.USER> SET DEBUG=1
- A @code{-} removes an existing watchpoint for the following variable.
- A @code{?} examines the status of a watchpoint for the following variable.
+ DEFAULT.USER> ZASSERT:DEBUG 1=1
- @example
- WATCH[@emph{:postcondition}] [+|-|?]@emph{var1}...,[+|-|?]@emph{varN}
+ DEFAULT.USER> ZASSERT:DEBUG 1=0
+ >> Error ZASSERT:  programmer assertion failed in SYSTEM::^%SYSINIT  [$STACK = 0]
+ >> ZASSERT:DEBUG 1=0
+                    ^
  @end example
+ @node ZBREAK
+ @section ZBREAK
+ @cindex ZBREAK
+ @cindex commands, ZBREAK
+ @cindex commands, debugging
+ @cindex commands, implementation-specific
+ @cindex commands, non-standard
+ @emph{FreeM Extension}
+ Sets or clears the @code{ZBREAK} flag@footnote{NOTE: FreeM team needs to investigate how @code{zbreakon} and @code{zbflag} affect program execution.}, based on the result of evaluating @emph{tvexpr}.
- The following example demonstrates turning watchpoint processing on and adding a watchpoint for global variable @code{^snw(1)}. It then changes the value of @code{^snw(1)}.
+ @emph{Syntax}
  @example
- DEFAULT.USER> WATCH
+ ZBREAK @emph{tvexpr}
- Watchpoints enabled.
- DEFAULT.USER> WATCH +^SNW(1)
- Added '^SNW("1")' to the watchlist.
- DEFAULT.USER> SET ^SNW(1)="new value"
- >> WATCHPOINT:  ^SNW("1") => 'new value' (changed 1 times)
  @end example
- The following example will remove that watchpoint:
+ @node ZCONST
+ @section ZCONST
+ @cindex ZCONST
+ @cindex commands, ZCONST
+ @cindex commands, non-standard
+ @emph{FreeM Extension}
+ Defines a local @emph{constant}, or variable that cannot be altered after its initial definition, provided the optional @emph{postcondition} is @emph{true} or omitted.
+ Constants must only be locals, and globals are not supported.
+ @emph{Syntax}
  @example
- DEFAULT.USER> WATCH -^SNW(1)
+ @code{ZCONST@emph{:postcondition} @emph{mref1}=@emph{initial-value1},...,@emph{mrefN}=@emph{initial-valueN}}
- Removed '^SNW("1")' from the watchlist.
- DEFAULT.USER> WATCH ?^SNW(1)
- '^SNW("1")' is not being watched.
  @end example
- @node WITH
+ @node ZEDIT
- @section WITH
+ @section ZEDIT
- @cindex WITH
+ @cindex ZEDIT
- @cindex commands, WITH
+ @cindex commands, ZEDIT
  @cindex commands, non-standard
  @emph{FreeM Extension}
- NOTE: This command may be deprecated and removed in future FreeM releases.
+ Edits a routine using an external editor. Uses environment variable @code{$EDITOR} if defined; otherwise, uses @code{vi}.
- Sets a prefix to be applied to all subsequent local variable or constant references.
  @emph{Syntax}
  @example
- @code{WITH@emph{:postcondition} @emph{var-prefix}}
+ ZEDIT@emph{[:postcondition]}
  @end example
- In the above single-argument form, sets the @code{$WITH} prefix to @emph{var-prefix}, provided that the optional @emph{postcondition} is either @emph{true} or omitted.
+ In its argumentless form, edits the currently-active routine, provided the optional @emph{postcondition} is @emph{true} or omitted.
- The @emph{var-prefix} argument may be a string literal or any valid FreeM expression.
+ @emph{Syntax}
  @example
- @code{WITH@emph{:postcondition}}
+ ZEDIT@emph{[:postcondition]} @emph{<routine-name>}
  @end example
- In the above argumentless form, clears the @code{$WITH} prefix, provided the optional @emph{postcondition} is either @emph{true} or omitted. Equivalent to @code{WITH ""}.
+ In its single-argument form, edits @emph{<routine-name>}, provided the optional @emph{postcondition} is @emph{true} or omitted.
+ Routine names must not be quoted, and must not included a leading caret (@code{^}).
- @node WRITE
+ @emph{Errors}
- @section WRITE
- @cindex WRITE
- @cindex commands, WRITE
- @node XECUTE
+ @code{ZEDIT} will raise @code{ZNOPGM} if the routine cannot be found, or there is no routine currently loaded in argumentless form.
- @section XECUTE
- @cindex XECUTE
- @cindex commands, XECUTE
- @node ZBREAK
+ @node ZGOTO
- @section ZBREAK
+ @section ZGOTO
- @cindex ZBREAK
+ @cindex ZGOTO
- @cindex commands, ZBREAK
+ @cindex commands, ZGOTO
- @cindex commands, debugging
  @cindex commands, implementation-specific
  @cindex commands, non-standard
  @emph{FreeM Extension}
- @node ZGO
+ In its single-argument form, enables @code{BREAK} mode and branches unconditionally to @emph{entryref}.
- @section ZGO
- @cindex ZGO
+ @emph{Syntax}
- @cindex commands, ZGO
- @cindex commands, implementation-specific
+ @example
- @cindex commands, non-standard
+ ZGOTO @emph{entryref}
- @emph{FreeM Extension}
+ @end example
+ In its argumentless form, resumes execution after a @code{BREAK}.
+ @emph{Syntax}
+ @example
+ ZGOTO
+ @end example
  @node ZHALT
  @section ZHALT
- Line 3397  In the above argumentless form, clears t
+ Line 3513  In the above argumentless form, clears t
  @cindex commands, non-standard
  @emph{FreeM Extension}
+ In its single-argumented form, @code{ZHALT} command is used to exit the FreeM process with a specific return value @emph{intexpr}.
+ @emph{Syntax}
+ @example
+ ZHALT @emph{intexpr}
+ @end example
+ In its argumentless form, @code{ZHALT} is synonymous with @code{HALT}.
+ @emph{Syntax}
+ @example
+ ZHALT
+ @end example
  @node ZINSERT
  @section ZINSERT
  @cindex ZINSERT
- Line 3433  Loads routine @emph{<routine-name>} into
+ Line 3565  Loads routine @emph{<routine-name>} into
  ZLOAD@emph{:postcondition} @emph{<routine-name>}
  @end example
+ @node ZMAP
+ @section ZMAP
+ @cindex ZMAP
+ @cindex commands, ZMAP
+ @cindex commands, implementation-specific
+ @cindex commands, non-standard
+ Maps global name @code{gvn} to be mapped to the non-default namespace @emph{expr V namespace}, provided the optional @emph{postcondition} evaluates to @emph{true} or is omitted.
+ @emph{Syntax}
+ @example
+ ZMAP[@emph{:postcondition}] GLOBAL @emph{gvn}=@emph{expr V namespace}
+ @end example
  @node ZNEW
  @section ZNEW
  @cindex ZNEW
- Line 3491  In its argumentless form, quits from @co
+ Line 3639  In its argumentless form, quits from @co
  @cindex commands, non-standard
  @emph{FreeM Extension}
+ @node ZTHROW
+ @section ZTHROW
+ @cindex ZTHROW
+ @cindex commands, ZTHROW
+ @cindex commands, non-standard
+ @emph{FreeM Extension}
+ Raises an error condition as long as the optional @emph{postcondition} is @emph{true} or omitted.
+ @emph{Syntax}
+ @example
+ @code{ZTHROW@emph{:postcondition} @emph{expr V error-code}}
+ @end example
+ @emph{Example}
+ @example
+ @code{ZTHROW "M102"}
+ @end example
  @node ZTRAP
  @section ZTRAP
  @cindex ZTRAP
- Line 3500  In its argumentless form, quits from @co
+ Line 3670  In its argumentless form, quits from @co
  @cindex commands, non-standard
  @emph{FreeM Extension}
+ Synonymous with @ref{ZTHROW}.
+ @node ZUNMAP
+ @section ZUNMAP
+ @cindex ZUNMAP
+ @cindex commands, ZUNMAP
+ @cindex commands, implementation-specific
+ @cindex commands, non-standard
+ Removes any mapping connecting @emph{gvn} to a non-default namespace, provided the optional @emph{postcondition} evaluates to @emph{true} or is omitted.
+ @emph{Syntax}
+ @example
+ ZUNMAP GLOBAL @emph{gvn}
+ @end example
+ @node ZWATCH
+ @section ZWATCH
+ @cindex ZWATCH
+ @cindex commands, ZWATCH
+ @cindex commands, debugging
+ @cindex commands, implementation-specific
+ @cindex commands, non-standard
+ @emph{FreeM Extension}
+ Sets a watchpoint on a global, local, or SSVN node.
+ @emph{Syntax}
+ In its @emph{argumentless} form, @code{ZWATCH} toggles watchpoints on and off, provided the optional @emph{postcondition} is @emph{true} or omitted.
+ @example
+ ZWATCH[@emph{:postcondition}]
+ @end example
+ In its @emph{inclusive} form, @code{ZWATCH} adds, removes, or examines watchpoints, provided the optional @emph{postcondition} is @emph{true} or omitted.
+ A @code{+} adds a new watchpoint to the following variable.
+ A @code{-} removes an existing watchpoint for the following variable.
+ A @code{?} examines the status of a watchpoint for the following variable.
+ @example
+ ZWATCH[@emph{:postcondition}] [+|-|?]@emph{var1}...,[+|-|?]@emph{varN}
+ @end example
+ The following example demonstrates turning watchpoint processing on and adding a watchpoint for global variable @code{^snw(1)}. It then changes the value of @code{^snw(1)}.
+ @example
+ DEFAULT.USER> ZWATCH
+ Watchpoints enabled.
+ DEFAULT.USER> ZWATCH +^SNW(1)
+ Added '^SNW("1")' to the watchlist.
+ DEFAULT.USER> SET ^SNW(1)="new value"
+ >> WATCHPOINT:  ^SNW("1") => 'new value' (changed 1 times)
+ @end example
+ The following example will remove that watchpoint:
+ @example
+ DEFAULT.USER> ZWATCH -^SNW(1)
+ Removed '^SNW("1")' from the watchlist.
+ DEFAULT.USER> ZWATCH ?^SNW(1)
+ '^SNW("1")' is not being watched.
+ @end example
+ @node ZWITH
+ @section ZWITH
+ @cindex ZWITH
+ @cindex commands, ZWITH
+ @cindex commands, non-standard
+ @emph{FreeM Extension}
+ NOTE: This command may be deprecated and removed in future FreeM releases.
+ Sets a prefix to be applied to all subsequent local variable or constant references.
+ @emph{Syntax}
+ @example
+ @code{ZWITH@emph{:postcondition} @emph{var-prefix}}
+ @end example
+ In the above single-argument form, sets the @code{$WITH} prefix to @emph{var-prefix}, provided that the optional @emph{postcondition} is either @emph{true} or omitted.
+ The @emph{var-prefix} argument may be a string literal or any valid FreeM expression.
+ @example
+ @code{ZWITH@emph{:postcondition}}
+ @end example
+ In the above argumentless form, clears the @code{$WITH} prefix, provided the optional @emph{postcondition} is either @emph{true} or omitted. Equivalent to @code{ZWITH ""}.
  @node ZWRITE
  @section ZWRITE
  @cindex ZWRITE
- Line 4411  A @code{REAL} is a numeric interpretatio
+ Line 4694  A @code{REAL} is a numeric interpretatio
  @cindex data types, STRING
  @cindex types, STRING
- A @code{STRING} is any data in FreeM.
+ The @code{STRING} is the fundamental FreeM data type. Other types are inferred from the context of their usage.
+ @subsection String Rules
+ The following rules apply to all FreeM strings:
+ @itemize
+ @item Must not exceed 255 characters
+ @item Must not contain @code{$C(0)}, @code{$C(201)}, or @code{$C(202)}
+ @end itemize
+ @subsection String Quoting Rules
+ Strings in FreeM must be surrounded in double quotes:
+ @example
+ SET MYSTRING="This is a string literal"
+ @end example
+ If you want to include double quotes inside of a string, simply double them:
+ @example
+ SET MYSTRING="This is a ""string literal"" with embedded double quotes"
+ @end example
  @node Custom Types (Classes)
  @section Custom Types (Classes)
- Line 4419  A @code{STRING} is any data in FreeM.
+ Line 4725  A @code{STRING} is any data in FreeM.
  @cindex types, custom
  @cindex classes
- See @ref{Classes}.
+ See @ref{Object-Oriented Programming}.
  @node Globals
  @chapter Globals
- Line 4450  Optionally, one or more comma-delimited
+ Line 4756  Optionally, one or more comma-delimited
  A value of up to 255 characters in length
  @end itemize
- The percent sign will force the named global into the @code{SYSTEM} namespace of the current FreeM environment.
+ A leading percent sign in the global name will force the named global into the @code{SYSTEM} namespace of the current FreeM environment.
  @node Creating Globals
  @section Creating Globals
- Line 4526  typedef struct global_header {
+ Line 4832  typedef struct global_header {
  @node Concurrency Control Overview
  @section Concurrency Control Overview
- Multitasking, multi-user FreeM applications must concern themselves with concurrent access to globals in order to maintain logical consistency and prevent concurrent writes from interleaving.
+ Multitasking, multi-user FreeM applications must concern themselves with conscientious management of concurrent access to globals in order to maintain logical consistency and prevent concurrent reads and writes from conflicting with each other.
- In FreeM, there are two mechanisms provided for managing concurrent global access: advisory locks, and transaction processing.
+ In FreeM, there are two mechanisms provided for managing concurrent global access: @emph{advisory locks}, and @emph{transaction processing}.
+ Advisory locks allow applications to voluntarily coordinate concurrent access to globals with the @code{LOCK} command, and require each application to check the @code{LOCK} status prior to accessing a global.
+ Transaction processing allows applications to delineate sets of global operations (sets, kills, etc.) as being part of a transaction, in which no operations are performed against the globals contained within the transaction until the transaction is committed. In addition, processes other than the one running the transaction will be forced to wait to access globals for either the duration of the commit phase (@emph{batch mode}), or for the entire duration of the transaction (@emph{serial mode}).
  @node Advisory Locks
  @section Advisory Locks
- Line 4537  In FreeM, there are two mechanisms provi
+ Line 4847  In FreeM, there are two mechanisms provi
  @section Transaction Processing
  @cindex transaction processing
- FreeM implements a significant subset of the transaction processing features from @emph{ANSI X11.1-1995}. This allows a series of global operations to be conducted all at once, either in batch mode (where concurrency is not disturbed), or in serial mode (where writes are guaranteed to be atomic, consistent, isolated, and durable).
+ FreeM implements a significant subset of the transaction processing features from @emph{ANSI X11.1-1995}. This allows a series of global operations to be conducted all at once, either in batch mode (where concurrent operation is not interrupted until the last possible moment), or in serial mode (where writes are guaranteed to be atomic, consistent, isolated, and durable).
  @subsection Theory of Operation
- Line 4616  The effect of this is that the operation
+ Line 4926  The effect of this is that the operation
  @cindex variables, local
  @cindex local variables
+ @menu
+ * Local Variables Overview::            The basics of locals.
+ * Creating Local Variables::            Creating locals with SET.
+ * Removing Local Variables::            Removing locals with KILL.
+ @end menu
+ @node Local Variables Overview
+ @section Local Variables Overview
+ FreeM @emph{local variables} have the same data structure as global variables, but are scoped to a single FreeM process, and stored in memory.
+ Each local comprises three elements:
+ @itemize @bullet
+ @item
+ An alphabetic name beginning with a letter or a percent sign (@code{%})
+ @item
+ Optionally, one or more comma-delimited subscripts, enclosed in parentheses
+ @item
+ A value of up to 255 characters in length
+ @end itemize
+ @node Creating Local Variables
+ @section Creating Local Variables
+ @cindex local variables, creating
+ To create a local variable, use the @code{SET} command:
+ @example
+ SET MYLOCAL("foo","bar")="this is the data value"
+ @end example
+ @node Removing Local Variables
+ @section Removing Local Variables
+ @cindex local variables, removing
+ To remove an entire local variable, you can use the @code{KILL} command with the unsubscripted name of the variable:
+ @example
+ KILL MYLOCAL
+ @end example
+ If you only want to remove part of a local variable, i.e., beginning at a certain subscript level, use the @code{KILL} command with a subscripted name:
+ @example
+ KILL MYLOCAL("foo")
+ @end example
+ This will remove only the @code{"foo"} subscript and all of its children.
+ If you only want to remove the data value at a specific subscript level, leaving the subscript itself intact, use @code{KVALUE}:
+ @example
+ KVALUE MYLOCAL("foo")
+ @end example
  @node Scoping
  @chapter Scoping
  @cindex scoping
+ By default, FreeM local variables and their values are scoped to the entire process, meaning that any function or subroutine can access and modify their values. This can lead to pernicious bugs.
+ M provides the @code{NEW} command to work around these issues. When @code{NEW} is called with a local variable as its argument, FreeM will scope the variable to the process stack frame in which the @code{NEW} command occured. When exiting the stack frame (i.e. with the @code{QUIT} command), FreeM will restore the variable to its value prior to being @code{NEW}ed.
+ @emph{Example}
+ @example
+ MYRTN ;
+   S J=1 ; set local variable J to 1
+   W J,! ; this will output "1"
+   D X   ; execute subroutine X
+   W J,! ; this will output "1", as the value of J was restored
+   Q
+   ;;
+ X ;
+   N J   ; stack J
+   S J=6 ; set its value to 6
+   W J,! ; this will output "6"
+   Q     ; quit from the subroutine, destroying its stack frame
+   ;;
+ @end example
+ @section Scoping Considerations for $TEST
+ In M, the truth value of comparisons, logic operations, and certain forms of @code{LOCK} is stored in the @code{$TEST} intrinsic special variable, which follows the same rules as any M local variable.
+ This is probably the most significant design flaw of the language, as the side effects of logic on @code{$TEST} lead to incredibly difficult bugs. However, M allows @code{$TEST} to be @code{NEW}ed, and FreeM provides the @code{THEN} command@footnote{From MDC Type A extension X11/1998-31} to help in the case of conditionals. @code{THEN} stacks @code{$TEST} to the end of the line.
+ When writing new M code in FreeM, we strongly suggest using @code{THEN} as follows:
+ @example
+ MYRTN ;
+   IF MYVAR=1 THEN DO SUBRT
+ @end example
+ This is instead of the traditional form:
+ @example
+ MYRTN ;
+   IF MYVAR=1 DO SUBR
+ @end example
+ @cartouche
+ @quotation
+ @emph{Style Recommendation}
+ Note that @code{THEN} is not in any currently published version of the @emph{Standard}, but is part of MDC Type A extension X11/1998-31. However, we recommend using @code{THEN} instead of favoring portability, as there is no defensible reason for this incredibly simple feature @emph{not} to be ubiquitous.
+ If you use other M implementations, you should bug the implementers to implement @code{THEN}, as it at least partially mitigates an inexcusable flaw in the design of M.
+ @end quotation
+ @end cartouche
  @node Decision Constructs
  @chapter Decision Constructs
  @cindex decision constructs
- Line 4663  The effect of this is that the operation
+ Line 5081  The effect of this is that the operation
  @cindex programming, object-oriented
  @menu
- * Classes::                         The basis of object-oriented programming.
+ * Classes::                             The organizing concept of object-oriented programming.
- * Inheritance::                     Basing one class upon another.
+ * Inheritance::                         Making one class derive from another.
- * Methods::                         Attaching code to a class.
+ * Methods::                             Attach code to classes.
- * Public and Private Variables::    Managing class member access.
+ * Public and Private Variables::        Determining accessibility.
- * Instantiating Objects::           Creating instances of classes.
+ * Instantiating Objects::               Creating instances of classes.
- * Determining Object Class::        Getting object information at runtime.
  @end menu
  @node Classes
  @section Classes
- @menu
- * Class Overview::                  Class basics.
- * Constructors::                    Managing object creation.
- * Destructors::                     Cleaning up.
- * Runtime Polymorphism::            Selecting methods at runtime.
- @end menu
- @node Class Overview
  @subsection Class Overview
  A @emph{class} is the primary organizing concept of FreeM support for object-oriented programming, and in FreeM, is simply an M routine with a few special properties:
- Line 4699  DESTROY(THIS) ; This is the destructor
+ Line 5107  DESTROY(THIS) ; This is the destructor
  The above example demonstrates general class syntax.
- @node Constructors
  @subsection Constructors
  A @emph{constructor} is an M entry point that is called when a new instance of a class is created.
- Line 4724  A constructor looks like this:
+ Line 5131  A constructor looks like this:
  In the above example, @emph{<superclass>} represents the name of a class from which this class should inherit. In this case, the @code{FRACTION} class inherits from the @code{OBJECT} class. Note that this is not strictly necessary in this case, as all classes in FreeM automatically inherit from @code{OBJECT}.
- @node Destructors
  @subsection Destructors
  A @code{destructor} is called when you @code{KILL} an instance variable. Its tag must be @code{DESTROY}, and it must take one argument (@code{THIS}).
- Line 4751  Inheritance is achieved by specifying th
+ Line 5157  Inheritance is achieved by specifying th
  CLASS(THIS,INIT):SUPERCLASS
  @end example
- @node Runtime Polymorphism
  @subsection Runtime Polymorphism
  You can achieve runtime polymorphism by subclassing, and defining methods in the subclass that match the names of existing methods in the superclass. Following FreeM inheritance rules, the overridden method in the subclass will be called, and the method in the superclass will not.
- Line 4781  DEFAULT.USER> W MYOBJ.MYMETHOD()
+ Line 5186  DEFAULT.USER> W MYOBJ.MYMETHOD()
  VALUE
  @end example
  @node Public and Private Variables
  @section Public and Private Variables
  FreeM supports private fields with the @code{:PRIVATE} specifier in the @code{SET} command, enforcing classical object-oriented data encapsulation. The @code{:PUBLIC} specifier is provided for completeness, and is the default.
- Line 4815  NEW MYSTR=$#^%STRING("myString")
+ Line 5220  NEW MYSTR=$#^%STRING("myString")
  This will create a local variable called MYSTR of type STRING, and initialize it with the value myString.
- @node Determining Object Class
+ @subsection Determining Object Class
- @section Determining Object Class
  To determine the class of any FreeM local variable, you will use the @code{$$TYPE()} method:
- Line 5413  Raised when you attempt to use multiple
+ Line 5817  Raised when you attempt to use multiple
  Raised when attempts are made to set @code{$ECODE} to an invalid error code value. Obsolete and replaced by standard error code @code{M101}.
  @item @code{ZASSERT} - @emph{programmer assertion failed}
- Raised when an @code{ASSERT} expression's result is not true.
+ Raised when an @code{ZASSERT} expression's result is not true.
  @item @code{ZUSERERR} - @emph{user-defined error}
  Raised when program code calls @code{THROW} with an error code argument for which the first character is @code{U}, or when @code{$ECODE} is set to an error code for which the first character is @code{U}.
- Line 5598  Raised when an attempt is made to use a
+ Line 6002  Raised when an attempt is made to use a
  @end table
- @node Debugging
- @chapter Debugging
- @cindex debugging
  @node System Configuration
  @chapter System Configuration
- Line 5609  Raised when an attempt is made to use a
+ Line 6010  Raised when an attempt is made to use a
  @section Installing FreeM
  @cindex installation
- @section Build Configuration
+ @subsection Installation Methods
- @cindex build configuration
- When configuring FreeM with the supplied @code{configure} script, there are some FreeM-specific options that may be used to compile in optional features, or exclude default ones:
+ FreeM allows the following installation methods:
  @table @asis
+ @item Binary Repository
+ For recent versions of the Ubuntu and Debian distributions of GNU/Linux, we provide package repositories from which FreeM may easily be installed. See the @emph{FreeM Wiki} for more information, and @emph{https://packages.coherent-logic.com} for instructions.
- @item @code{--enable-mwapigtk} (EXPERIMENTAL)
+ If available, this is the simplest method of installing FreeM.
- Enables experimental support for the M Windowing API using the GTK3 libraries. Requires that you have GTK 3 libraries, their headers, and their dependencies installed on your system.
+ @item Binary Packages
+ We provide binary packages of FreeM for @emph{dpkg} and @emph{rpm}-based distributions of GNU/Linux, and @emph{pkgadd} packages for Solaris 8-10. If you cannot use repositories, this is the easiest option.
+ See @emph{https://freem.coherent-logic.com/binaries.cfm} for downloads and instructions.
+ @item Source Tarball
+ If you prefer installing from source, we recommend that you download the latest @emph{.tar.gz} file from @emph{https://freem.coherent-logic.com/downloads.cfm}, and follow these steps:
+ @example
+ $ gunzip freem-@emph{<version>}.tar.gz
+ $ tar xf freem-@emph{<version>}.tar
+ $ cd freem
+ $ ./configure # see the Build Configuration section for optional flags
+ $ make
+ $ sudo make install
+ @end example
- Please consult your operating system's documentation for the correct commands to install the required libraries.
+ Once this process has been completed, you may proceed to @emph{Initial Configuration}.
- @emph{Example}
+ Installation from source archive is the most challenging but flexible supported option for advanced users.
+ @item CVS Repository
+ If you wish to try the bleeding-edge development version of FreeM, you may do so by following these steps:
- @example
+ @verbatim
- $ ./configure --enable-mwapigtk
+ $ cvs -d :pserver:anonymous@cvs.coherent-logic.com:/home/cvsroot co freem
+ $ cd freem
+ $ ./autogen.sh
+ $ ./configure # see the Build Configuration section for optional flags
  $ make
  $ sudo make install
- @end example
+ @end verbatim
+ Once this process has been completed, you may proceed to @emph{Initial Configuration}.
+ This installation method is by far the most complicated, and is intended only for those who wish to contribute to FreeM development. It is not intended for end users, and no technical support will be provided.
- @item @code{--enable-berkeleydb} (EXPERIMENTAL)
+ See the @emph{Contributor Guide} on the @emph{FreeM Wiki} for more information.
- Enables experimental support for using the BerkeleyDB database as a global handler for FreeM global namespaces. Requires that you have the @code{libdb} library, headers, and dependencies installed on your system.
+ @end table
+ @subsection Build Configuration
+ @cindex build configuration
+ When configuring FreeM with the supplied @code{configure} script, there are some FreeM-specific options that may be used to compile in optional features, or exclude default ones:
+ @table @asis
+ @item @code{--enable-mwapi} (EXPERIMENTAL)
+ Enables experimental support for the M Windowing API (ANSI @emph{X11.6-1995}) using the OSF/Motif widget toolkit. Requires that you have the @code{X11}, @code{Xt}, @code{ICE}, and @code{Xm} libraries, as well as all of their C header files.
  Please consult your operating system's documentation for the correct commands to install the required libraries.
  @emph{Example}
  @example
- $ ./configure --enable-berkeleydb
+ $ ./configure --enable-mwapi
  $ make
  $ sudo make install
  @end example
+ @item @code{--enable-newglobals} (EXPERIMENTAL)
+ Enables a new and modernized global handler. This global handler has a number of known bugs, and thus should be used with caution.
- @item @code{--without-readline}
+ Note that global files created in the default global handler are incompatible with the new global handler, and vice-versa. You will need to back up and remove all globals in your environments when switching global handlers.
- Builds FreeM without GNU @code{readline} support, even if @code{readline} is installed on your system.
- Please note that building FreeM without GNU @code{readline} will also exclude REPL functionality and all direct-mode utility commands, i.e. @code{events}, @code{tdump}, @code{shmstat}, and @code{shmpages}.
  @emph{Example}
  @example
- $ ./configure --without-readline
+ $ ./configure --enable-newglobals
  $ make
  $ sudo make install
  @end example
  @end table
+ @subsection Initial Configuration
+ Once FreeM is installed, you will need to configure it:
+ @enumerate
+ @item Create a user and group, each named @emph{freem}, under which FreeM will run
+ @item Add any user accounts that will need to run FreeM to the @emph{freem} group
+ @item Have all users added in step 2 sign out and sign in for the new group membership to take effect
+ @item Run @code{fmadm configure} with superuser privileges to create the @code{DEFAULT} environment with @code{SYSTEM} and @code{USER} namespaces and default after-image journal settings, and populate the bundled vendor routines
+ @item Run @code{fmadm start environment} with superuser privileges to start the @code{DEFAULT} environment
+ @item Make sure the environment is ready by running @code{fmadm status environment} with superuser privileges
+ @end enumerate
+ @subsubsection Creating Additional Environments
+ To create additional environments, do the following steps:
+ @enumerate
+ @item Create a new user and group for the environment @emph{(optional)}
+ @item Run @code{fmadm configure -e=@emph{<environment>} -u=@emph{<username>} -g=@emph{<groupname>} [-E=@emph{true|false}]} @emph{(the @code{-E} flag enables or disables the environment)}
+ @item Run @code{fmadm start environment -e=@emph{<environment>}} to start the environment
+ @item Run @code{fmadm status environment} to make sure the environment is healthy
+ @end enumerate
+ @subsubsection Additional Customization
+ See the FreeM @emph{environment catalog} at @code{@emph{$PREFIX}/etc/freem/env.conf}, and the @emph{fmadm}(1) @code{man} page for more information.
+ @emph{$PREFIX} represents the root location of your FreeM installation. This can be @code{/usr/local}, @code{/}, or others, depending on how FreeM was built and installed.
  @node Accessing FreeM from C Programs
  @chapter Accessing FreeM from C Programs
- Line 6087  int main(int argc, char **argv, char **e
+ Line 6547  int main(int argc, char **argv, char **e
  @cindex fmadm
  The @code{fmadm} utility is the preferred method of managing a FreeM installation, and will eventually replace all of the existing utilities.
- Unlike the existing, legacy utilities, @code{fmadm} presents a consistent, simple interface for all FreeM management tasks, and is namespace-aware.
+ In support of FreeM operators, @code{fmadm} presents a consistent, simple interface for all FreeM management tasks, and is namespace-aware.
- This appendix will document each @code{fmadm} facility as it is implemented, until all of the legacy utilities have been replaced.
+ This appendix will document each @code{fmadm} facility as it is implemented.
  The @code{fmadm} utility's functions all follow the below, consistent syntax:
- Line 6182  Supported actions are @code{list} and @c
+ Line 6642  Supported actions are @code{list} and @c
  @end table
- @node FreeM Legacy Utilities
- @appendix FreeM Legacy Utilities
- @cindex utilities, legacy
- @section Global Compactor (gcompact)
- @cindex utilities, legacy, gcompact
- Compacts the specified global in place.
- @emph{Syntax}
- @example
- gcompact @emph{/path/to/global/file}
- @end example
- @section Block Examiner (gfix)
- @cindex utilities, gfix
- The @emph{gfix} interactive utility program permits navigation of the B-tree structure of the specified global a block at a time.
- @emph{Syntax}
- @example
- gfix @emph{</path/to/global/file>}
- @end example
- @section Global Repair Tool (grestore)
- @cindex utilities, legacy, grestore
- This utility will fix problems with the specified global.
- @emph{Syntax}
- @example
- grestore @emph{</path/to/global/file>}
- @end example
  @node FreeM VIEW Commands and Functions
  @appendix FreeM VIEW Commands and Functions

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