Marking scheme

Hi.

I have read articles which talk about depth and breadth and the point-explain approach and have seen every new and main working earning from .5 to 1(depending upon their complexity).

Iv heard teacher assistants say ‘for define/criteria statements its .5 and for justify its 1’. Iv even heard teachers say ‘.5 for identification, then talk(e.g. the problem, strategy clashes, counter arguments, what was being done etc.) for 1 mark’.

What is the marking scheme used in professional papers like p3 for both points and workings and how can i judge the marks for myself during practice?