HP DDL D40 Reference Manual page 113

Definition Attributes
Requesters generated by the Pathmaker product enforce the MUST BE
constraints; programs written by users must be coded to enforce these constraints
as well.
MUST BE Clause Examples
In this example, the MUST BE clause defines the acceptable ranges of values for days
in a month and months in a year:
DEF date.
02 day
02 month
02 year
END
If you specify the same MUST BE values frequently, you can define the values as
constants; for example:
CONSTANT sales
CONSTANT shipping
CONSTANT personnel
DEF company.
02 department
88 sales
88 shipping
88 personnel
END
Notice that you can also use the constant names in condition-name clauses associated
with the definition.
Data Definition Language (DDL) Reference Manual—426798-002
PIC 9(2)
MUST BE 1 THROUGH 31.
PIC 9(2).
MUST BE 1 THROUGH 12.
PIC 9(2).
VALUE 1.
VALUE 2.
VALUE 3.
TYPE BINARY 16
MUST BE sales,
shipping,
personnel.
VALUE sales.
VALUE shipping.
VALUE personnel.
6- 19
MUST BE Clause