Comment by professoretc

The post I was replying to said,

> UB was coined only in the first C standard, in 1989. Prior to that there was no "If you do this, anything can happen".

I.e., the context is, before UB existed as a concept, how would these things be categorized. And I was trying to offer the correction that, before UB existed, it wasn't "all behavior is defined" but rather many behaviors depend on your particular local environment. While that may technically be implementation defined, the current standard requires that implementation defined be documented, and UB-like edge cases were most definitely not documented anywhere consistently in the old days!