Empirically, it *is* necessary to explain that equating R0 though R15 to register numbers other than the ones implicit in the names is a cardinal sin.
-- Shmuel (Seymour J.) Metz http://mason.gmu.edu/~smetz3 ________________________________________ From: IBM Mainframe Assembler List [[email protected]] on behalf of Jonathan Scott [[email protected]] Sent: Thursday, April 30, 2020 4:59 AM To: [email protected] Subject: Re: *-* The use of "*-*" to denote a dummy zero field which may be filled in or overriden later (for example, the length in an executed MVC instruction) is a very widespread notation convention in mainframe assembler. It is used in examples in the HLASM Programmer's Guide, for example the following executed instruction in the TERM user exit example: UPPERSTR OC OPENPARM(*-*),0(BUFREG) Move and uppercase string This is just part of the common notation used by assembler programmers, which should preferably be mentioned during assembler training courses. I do not think it needs explaining when used any more than it should be necessary to explain any other common convention, for example that R1 is a name with value 1 conventionally used to refer to general register 1. Jonathan Scott, HLASM IBM Hursley, UK
