Used to set the text of the messages subject.
You would normally call this function to set a Subject but it is not mandatory.
This example shows only this function. See the example for MAIL_START which defines all details of an Email message and then sends it by using Built-In Functions.
********** COMMENT(Set Subject text)
USE BUILTIN(MAIL_SET_SUBJECT) WITH_ARGS('Testing Email Built-In Functions') TO_GET(#LEM_RETC)