$ECode

Contains a list of errors since it was last cleared

$STack

Contains the current level of DO/XECUTE nesting from a base of zero (0).

$STack()

Returns information about the M virtual stack context, most of which freezes when an error changes $ECODE from the empty string to a list value.

ZBreak

Establishes a temporary breakpoint, with optional count and M action.

ZCOMpile

Invokes the GT.M compiler without a corresponding ZLINK.

ZContinue

Continues routine execution from a break.

ZEDit

Invokes the UNIX text editor specified by the EDITOR environment variable.

ZGoto

Removes zero or more levels from the M invocation stack and transfers control.

ZLink

Includes a new or modified M routine in the current M image; automatically recompiles if necessary.

ZMessage

Signals a specified condition.

ZPrint

Displays lines of source code.

ZSHow

Displays information about the M environment.

ZSTep

Incrementally executes a routine to the beginning of the next line of the specified type.

ZSYstem

Invokes the shell, creating a forked process.

ZWRite

Displays all or some local or global variables.

$ZCSTATUS

Contains the value of the status code for the last compile performed by a ZCOMPILE, ZLINK or auto-ZLINK.

$ZEDit

Contains the status code for the last ZEDit.

$ZLEVel

Contains the current level of DO/EXECUTE nesting.

$ZMessage()

Returns the text associated with an error condition code.

$ZPOSition

Contains a string indicating the current execution location.

$ZPROmpt

Controls the symbol displayed as the direct mode prompt.

$ZROutines

Contains a string specifying a directory list containing the object, and optionally the source, files.

$ZSOurce

Contains name of the M source program most recently ZLINKed or ZEDITed; default name for next ZEDIT or ZLINK.

$ZStatus

Contains error condition code and location of the last exception condition occurring during routine execution.

$ZSTep

Controls the default ZSTep action.

$ZSYstem

Contains the status code of the last ZSYSTEM.