grammatical number - Inconsistency regarding plural: why do we write "results file" but also "result list"?

How come it is ok to write "results file",
while you must write "result list" rather than "results list"?

Answer

Technically, either version is grammatically correct. However, the word "list" implies a plural amount of the item, therefore stylistically people only use a singular in front of "list". However, the word "file" does not imply a plural amount (technically you could have a file with only one result), so you can use plural form in order to clarify.