The AssertMayMod and AssertNoMod assertions are used at a CALL statement, to indicate that the routine being called either might modify ( MAYMOD) the variables listed on the directive, or definitely does not ( NOMOD) modify the listed variables.
The CSRD directive form of the AssertMayMod and AssertNoMod assertions is:
CSRD$ MAYMOD a, b
An example of its usage is as follows:
CSRD$ MAYMOD a, b
call sub (a, b, c)
. . .