The name of a DS cannot be described as a numeric variable. It is therefore recommended to use a DS name that is not defined as a variable and to define a numeric field which gathers together all DS fields. This field cannot exceed 30 characters (on the AS/400, in RPG generation).
Suggested approach:
In the example below, "Field1" is numeric (a date for instance).
DS DS01 FIELD1 FIELD2,1 FIELD3,5 where DS01 is not a variable.
In above case, DS01 cannot be used as a variable.