This Knowledge Document explains why the use of Date Tables are recommended over Calendars. Date Tables are more flexible to use and easier to maintain.
Date Tables can handle all criteria keywords that are used to determine when jobs and schedules should be added to the workload. As a rule, one Date Table (DATETAB) will be able to handle the majority of the jobs and schedules for selection. Sites using Calendars will find that many calendars have to be defined to accommodate job and schedule selection. For example, two jobs both running on Friday but one job does not run on the last Friday of the month. This requires two defined calendars, but only one Date Table.
Date Tables are easier to define and to alter. "W" is used to indicate a work day, and all others are holiday or non-workdays. The last day of the month is identified with an "M", and the last day of the year with a "Y" which can be altered by coding a "Y or M" on the actual processing of month end or year end. They can be defined with Monday to Friday as workdays or as an offset week, such as Sunday to Thursday.
Date Tables are flexible and are simple to use. In addition to the CALENDAR criteria, extended date criteria keywords such as WDAY (workday), WDOM1 (1 st work day of the month), WWOM-2 (2 nd to the last week of the month), RD15=+01 (1 st workday after the 15 th day) and many more are available.
Multiple Date Tables with the same name can also be defined but with a different accounting code. For example, DATETAB with accounting code of A and DATETAB with accounting code of B. The Date Table would be defined with an "A" on the accounting days. Criteria of BDAY will use the DATETAB with accounting code of B.
CA strongly recommends the use of Date Tables instead of Calendars.
CA Scheduler JM Online Guide, Chapter 8.2 Date Tables and Chapter 8.3 Calendars.