Sounds like you’re referring to the Appendix to the Rulebook (ARB)? I mentioned ours a while ago as I thought all TOCs had a variation. It’s basically a rulebook which encompasses certain modules and is generally more restrictive based on the given TOC’s own expectations. Some things are extra, and aren’t in the rulebook.
This is the case in point as to why doing no more than 20mph, 200yrds from a red signal shouldn’t be based on the AWS magnet. At most locations I get my speed down to 15 ish mph at an AWS magnet based on route knowledge (our policy is 20mph apart from leaf fall when it’s 10), but the signalling on the way in to and out of Portsmouth is so close together, it’s unlikely there’s the standard(ish) distance between AWS ramp and signal (I mean, I’ve never checked, but it appears much closer together). 15 would probably suffice in most cases at any AWS magnet, but reduced during leaf fall.