The HLASM team works with the architects to define new instructions for each new IBM processor in an APAR fix which is released around the time the processor becomes available, and for recent levels the OPTABLE name has matched the IBM hardware name (although there is no guarantee of how long this can continue). The policy when I was on the team was for HLASM to close the APAR on the hardware announcement day (to avoid pre-announcing the new instructions) so the PTF would be available within a few days after that, for use by pre-GA customers, but I did note that it wasn't quite so prompt for z17 after I retired (although the APAR had been prepared months in advance).
There are a few cases where additional extended mnemonics for existing instructions (such as LFI) were added to HLASM as part of a later instruction set. Those mnemonics were not retrofitted to previous OPTABLE levels because of potential compatibility problems, as they could in theory clash with existing user-defined mnemonics for sites using the previous OPTABLE, so the OPTABLE in which they appear is not the same as the level in which the base instruction was first supported. From a HLASM point of view, the documented OPTABLE is still the first one which supports them, but in some cases code using these extended mnemonics could execute successfully on older hardware levels. Jonathan Scott -----Original Message----- From: IBM Mainframe Assembler List <[email protected]> On Behalf Of Seymour J Metz Sent: 24 October 2025 14:38 To: [email protected] Subject: Re: LOAD ON CONDITION Does that correlate to the actual processor, or only when it was added to HLASM? -- Shmuel (Seymour J.) Metz http://mason.gmu.edu/~smetz3 עַם יִשְׂרָאֵל חַי נֵ֣צַח יִשְׂרָאֵ֔ל לֹ֥א יְשַׁקֵּ֖ר
