This is about scaling between different subjects which is not the same thing as what I said in my previous post. It's very new to me though, nice find Nadia. Basically it says that some subjects may be relatively easier to get higher score than another subject. For example, specialist maths might be harder to score than maths method, so someone would have had unfair advantage if he took maths method compared to specialist maths. Say an average person is able to score 190 for maths method but they are only able to score about 160 for specialist. The scaling will then be done by, say, increasing the specialist's scores so that people getting 160 will now get 190 so that the scores are comparable with people doing methods.
Check out our ReCom wiki
Do contribute by writing or editing the existing articles so that everyone now and in the future can benefit from it!