Without actually knowing, i'd guess that would generate bytecode's that could be modified later by patching the resulting binary ?
I remember few buddies using similar pattern in ASM that just added n NOP's into code to allow patching and thus eliminating possible recompilation..
I suspect that’s it.
There was a lot of self-modification, going on, in those days. Old machine language stuff had very limited resources, so we often modified code, or reused code space.