The CLASS clause relates a name to the specified set of characters listed in that clause.
CLASS Clause - Format >>-CLASS--class-name-1--+----+----------------------------------> '-IS-' .---------------------------------------. V | >----literal-4--+------------------------+-+------------------->< '-+-THROUGH-+--literal-5-' '-THRU----'
The value of each literal specifies the relative position, or ordinal number, of a character within the EBCDIC character set. Appendix C. EBCDIC and ASCII Collating Sequences lists the ordinal number for each character in the EBCDIC collating sequence.
Cannot be specified
as floating-point literals, DBCS literals, or national literals. 
If nonnumeric, the literal is the actual character within the EBCDIC character set. If the value of the nonnumeric literal contains multiple characters, each character in the literal is included in the set of characters identified by class-name.
If the nonnumeric literal is associated with a THROUGH phrase, it must be one character in length.