I had also been using the grammatical metaphor recently in some off-line discussions, to try and explain visibility. The one interesting nugget that emerged from that exercise, was that application protocol headers are adverbs, as they modify the verb (method). So a GET with an If-Modified-Since header, is a “conditional GET”, but – and to tie this back to visibility – it’s still a GET, the same way that “eat quickly” still describes the action of eating, whether or not you know what “quickly” means.
Yes, it’s a slow news day. 8-)