Hola Damaris, la instruccion es SUBDUR y te sirve para calcular un tiempo.
aqui te anexo la estructura, espero te sea de utilidad.
SUBDUR Examples
Figure 325. SUBDUR Operations
CL0N01Factor1+++++++Opcode(E)+Factor2+++++++Result++++++++Len++D+HiLoEq....
* Determine a LOANDATE which is xx years, yy months, zz days prior to
* the DUEDATE.
C DUEDATE SUBDUR XX:*YEARS LOANDATE
C SUBDUR YY:*MONTHS LOANDATE
C SUBDUR ZZ:*DAYS LOANDATE
* Add 30 days to a loan due date
*
C SUBDUR -30:*D LOANDUE
* Calculate the number or days between a LOANDATE and a DUEDATE.
C LOANDATE SUBDUR DUEDATE NUM_DAYS:*D 5 0
* Determine the number of seconds between LOANDATE and DUEDATE.
C LOANDATE SUBDUR DUEDATE NUM_SECS:*S 5 0