Examining the Source String
You have already seen that an argument string is passed to a prefix
macro when it is invoked. A source string is also passed.
00007 parse source . . . . . name .
00008 arg pref func pline op extraLine 7 parses the source string according to the template shown. In this example, the source string is used to get the name of the prefix macro as the user entered it (without operands). Later, you will see how the macro uses name to determine if it was invoked in its simple form (L) or block form (LL).
The source string is described in detail in z/VM: REXX/VM Reference.
In line 8, the argument string is parsed. For now, note that pline is the line number of the prefix area, and op is the optional operand.
The rest of the argument string is described later in this chapter. See Examining the Argument String.
In this example, if the user entered L8 in the prefix area of line 3 of a file, name would be L, pline would be 3, and op would be 8.