As some of you may be aware, back in 2013 while working in the HLASM team I created an IBM internal web document "HLASM z/Architecture instruction set overview" summarizing all instructions supported by HLASM in tables by type of instruction and operand types plus information about the required hardware instruction set level, and I linked each mnemonic to the relevant instruction topics in a home-made web version of the z/Architecture Principles of Operation, which also had a web front-end to look up instructions by mnemonic (plus HLASM instructions and common z/OS macros which it linked to in IBM Docs). For me, that was always far more useful than the reference summary. It was created originally as a "proof of concept" in the hope that the architects could create something similar that would be officially supported, but the process of creating it exposed so many complexities with the internals (which were only ever set up to produce the PDF) that the amount of work needed to fix it was way too much to be practical. Later on, the architects agreed that something like that could at least be released on an "as-is" basis without official support, but I never managed to find a way through the administrative complexities needed to make it available externally. It still exists, and it was at the z16 level and updated ready for z17 before I retired last February.
In general, I agree that for details of how things work, Principles of Operation is the definitive source, but my overview gives table of instructions of many types, grouped by function, for example for signed arithmetic, bit manipulation and so on, indicating what types and sizes of operands are supported, and what hardware level they require. That is what I usually needed to know. So if you can persuade IBM (in particular the HLASM team) to make that available, I think that would be much more useful than the Reference Summary! Jonathan Scott
