EQUALS insures that the original order of equal-keyed records is preserved. These records will be in the same order in the output file as they were in the sort input file. For a merge, equal-keyed records from the lowest-numbered SORTINnn file are written before those from the second input file, and so on. With NOEQUALS, there is a random element to the order in which records with identical control fields will appear in the output. With or without EQUALS, MERGE preserves the order of equal-keyed records within any one data set.
If EQUALS is in effect in an application with SORTMInn data sets, the order of equal-keyed records within each SORTMInn file will be preserved. In addition, equal-keyed records from the lowest-numbered SORTMInn file will be written before those from the second SORTMInn file, and so on.
When used in conjunction with SUM or DUPKEYS, EQUALS indicates which of the equal-keyed records will be preserved, containing the sum or DUPKEYS minimum, maximum, or average values: the record occurring first in SORTIN (for a sort), or drawn from the SORTINnn data set with the lowest nn number (for a merge) will contain the calculated fields.
The EQUALS option can also be specified on the SORT/MERGE control statement. The specification on the control statement takes precedence over the specification in the PARM field.