The validation of mixed strings depends on the instruction, operator, or function. If you use a mixed string with an instruction, operator, or function that does not allow mixed strings, this causes a syntax error.
'ab<cd' -> INCORRECT - not paired
'<.A<.B>.C> -> INCORRECT - nested
'<.A.BC>' -> INCORRECT - odd byte length
The
end of a comment delimiter is not found within DBCS character sequences.
For example, when the program contains /* < */, then
the */ is not recognized as ending the comment because
the scanning is looking for the > (SI) to go with the < (SO) and not looking for */.When a variable is created, modified, or referred to in a REXX program under OPTIONS EXMODE, it is validated whether it contains a correct mixed string or not. When a referred variable contains a mixed string that is not valid, it depends on the instruction, function, or operator whether it causes a syntax error.
The ARG, PARSE, PULL, PUSH, QUEUE, SAY, TRACE, and UPPER instructions all require valid mixed strings with OPTIONS EXMODE in effect.