Structured system variables (ssvn in metalanguage terminology) behave like global variables when used as parameters of the functions $DATA and $ORDER. When used in arguments of SET, MERGE and KILL commands, their behavior is different: either such usage is not allowed, but if it is allowed, there usually is a side-effect that is specific for the structured system variable in question.
In general, the structured system variables provide a directory for a specific aspect of the M[UMPS] language. In a number of cases, the structured system variables are used to manipulate 'meta-information' about the entities that are described in them.
Names of structured system variables may be returned by references to the function $QUERY. In such cases, a "canonic" form of the name will be returned, in which all parts that may be abbreviated are spelled out fully, and in which all parts that are case insensitive are spelled in upper case only.
This document is © Ed de Moel, 1995-2005.
It is part of a book by Ed de Moel that is published under the title "M[UMPS] by Example" (ISBN 0-918118-42-5).
Printed copies of the book are no longer available.
This document describes the various structured system variables that are defined in the M[UMPS] language standard (ANSI X11.1, ISO 11756).
The information in this document is NOT authoritative
and subject to be modified at any moment.
Please consult the appropriate (draft) language standard for an authoritative definition.
In this document, information is included that will
The MDC cannot guarantee that these 'next' standards will indeed appear.