Data set mask rules

The following rules apply to the special characters in a data set mask:

You can separate data set qualifiers with periods, “.”.
Each qualifier has a maximum length of eight characters. The maximum length for the entire data set mask is 44 characters.
A “%” represents a single character position. “%%%” represents three character positions.
A single “*” by itself indicates that at least one qualifier is needed to occupy that position. A “*” within a qualifier means that zero or more characters can be present.
A qualifier can be a single “*”
A “**” means that zero or more qualifiers can be present.
A “**” cannot appear with any other characters within a qualifier.
Three or more adjacent “*” are not allowed within a qualifier.
The read-only variables which cannot be used for comparisons are: &ACSENVIR, &DSNTYPE, &DSORG, &DSTYPE, &LABEL, &RECORG, and &XMODE.