Rules As Written (RAW) is a reference to the text of published works with any relevant errata, offical FAQ, and forum clarifications by GURPS authors that may exist, without any workarounds, house rules, or common variants. Often the subject of Murphy's Rules when it flies in the face of logic...or common sense.
Rules as Interpreted (RAI) is not much help especially if the text says one thing and the diagram says another (as with Area Spells) or there have been changes in the rules that have not been make their way to older material (as with the way Partially Limited Magery works in GURPS Thaumatology vs the way it worked in the Basic Set).