As I understand it, IBM uses the word "assembler" to describe the compiler for this language and "assembly" to describe the process which it performs.
And we use "Assembler language" to describe the language supported by the assembler (where some other environments use "assembly language"). Note however that language statements include "machine instructions", "assembler instructions" and "macro instructions", so not every statement is considered an "assembler instruction": https://www.ibm.com/docs/en/hla-and-tf/1.6?topic=introduction-assembler-language Back in 1974 when I was a student working at IBM Hursley, I frequently wrote System/370 code for testing purposes in hex using TSO test because it was much quicker than running the assembler. Within a few days, I was familiar with the hex codes for all common problem state instructions (excluding floating point), which was very useful for dump reading. Of course, there were less than 100 such instructions at the time, and many of them followed simple patterns! Jonathan Scott, HLASM IBM Hursley, UK
