Ahh
I know that there are few para. that require other para. to be issued, and those are listed in the para - for example, to get North Polar Ops, you also need Ops in Areas of Mag Unreliability.
I just did a search on WATRS in FSIMS, and it brought up 8900.1 4-1-5 - Special Navigation Areas of Operation, and that looks like it defines the specific requirements for the various defined parts of the world, and whats need to operate where.
Specific WATRS rules are in there, and the cross refs to other OpSpecs Paras required.
HTH