To work to rule is to do exactly what the rules require and no more. Work to rule for a fortnight, a work to rule.
It is a form of industrial action that breaks nothing, since the rules are being followed. It works precisely because most organisations depend on people doing more than the rules say.
1phrasework to ruleDoing exactly what the rules require and no more.
“The drivers agreed to work to rule rather than strike.”
work to rule is a phrase.
work-to-rule Deverbal from work to rule#Verb.
Etymology from Wiktionary, CC BY-SA
Practised in Work & Careers