When
the DATA step contains a MODIFY statement, SAS writes the current
observation back to its original place in the SAS data set. This action
by default occurs as the last action in the step as if a REPLACE statement
were the last statement in the step. However, you can override this
default behavior by explicitly adding the OUTPUT, REPLACE, or REMOVE
statement.
You can use the automatic
variable _IORC_ with the %SYSRC autocall macro to test for specific
I/O error conditions that are created when you use the BY statement
or the KEY= option in the MODIFY statement. The automatic variable
_IORC_ contains a return code for each I/O operation that the MODIFY
statement attempts to perform. The best way to test for values of
_IORC_ is to use the mnemonic codes that are provided by the SYSRC
autocall macro.