Tuesday, June 23, 2009

Access to memory sequences in Unicode programs

The following (in some cases obsolete) statements access data objects that are stored in the memory as an equally spaced sequence:

  • DO ... VARYING
  • WHILE ... VARY
  • ADD ... THEN ... UNTIL
  • ADD ... FROM ... TO

In the DO and WHILE loops in Unicode programs, all data objects of the sequence must be compatible and either be structure components that belong to the same structure, or subareas of the same data object specified using offset/length specifications. In Unicode programs, a RANGE must also be entered if it cannot be statically recognized that the data objects involved are components of the same structure. Otherwise, the permitted memory area is determined from the smallest possible substructure.

When memory sequences are added using ADD, in Unicode programs, all data objects of the sequence must be components of a structure. If this cannot be statically recognized in the syntax check, a structure must be specified using the addition RANGE.

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