from the command
select * from syscat.tables
you can find a table called:
    TABSCHEMA: ADSM
       TABNAME: MGMTCLASSES
   CREATE_TIME: 1996-04-25 14:31:19.025065
      COLCOUNT: 12
INDEX_COLCOUNT: 3
  UNIQUE_INDEX: TRUE
       REMARKS: Management classes

then you can do:
tsm: ADSM>select * from syscat.columns where tabname='MGMTCLASSES'

and from that you can see/find a column name called:
   TABSCHEMA: ADSM
     TABNAME: MGMTCLASSES
     COLNAME: CLASS_NAME

then you can do (your answer):
tsm: ADSM>select class_name from mgmtclasses

CLASS_NAME
------------------
10_DAY_RETENTION
10_DAY_RETENTION
30_DAY_RETENTION
5_DAY_RETENTION
60_DAY_RETENTION
90_DAY_RETENTION

etc...