prefixes - Prefixing a two-word technical term with "sub-"

I have the term "verification code" and need a term for a particular code that is part of it. Normally, if the term were only "code", I'd use "subcode". How would I correctly prefix "verification code" with "sub-" such that the meaning is clear?

Answer

You would use "verification subcode". You are possibly better off picking a term that denotes the function of the "subcode" and calling it a prefix.