Thanks WF am well aware about the rules of heading assignment!! I was asking about a specific case.
I ask because I was flying the other day and after being given a final heading to intercept by ATC (leaving us high) the PF re-adjusted his heading saying to me "once you are cleared for the approach you can adjust your heading as you need to establish onto the LOC". Now I hadn't heard that before so on the ground I asked him where I could find this information written down and he wasnt sure.
I appreciate any clarification and any thoughts about this specific case and if there is any written rule anywhere anyone knows about.