DCL: MATH1: Summary: FORTRAN77 Standard
In the early FORTRAN, delivery of data by arguments was a time-consuming
process, so in the past, there was an overuse of COMMON statements for delivering data from the main program to the subroutines. However, at the
present, the time is takes for data delivery by the two methods are nearly the
same. However, the COMMON statement has the disadvantage of making it unclear as to
which subroutine the value had been assigned to. Therefore, to improve
readability, the user is advised against using a COMMON statement for
delivering data to the subroutine.
In DCL, arguments are used for data delivery to the subroutine instead of a COMMON statement, unless there is a special need (such as securing work area).