ugly: the docs linked to above were to the CivilAir website, so probably not much point venting your anti-BillGates spleen here on the subject
And even if you "don't want to make Bill Gates rich" you can probably read the above docs using OpenOffice for free anyway.
Transition Layer and
ferris: Isn't it suggested that you tune to the relevant aerodrome frequencies (typically 126.7 I think) near to your track when
en route for this reason? So instead of broadcasting the impending departure to the whole region on the area frequency, aircraft B's initial call would have been on the CTAF (say) and if aircraft A was employing good airmanship he would've been monitoring same whilst passing nearby.
This is how it works in many places - here in the UK, for example, if in class G and flying nearby to an airfield
en route at low-ish levels, and if you were not in receipt of some other traffic service (e.g. LARS), one might typically tune the TWR, AFIS or RADIO frequency when within say 10 miles or so. I just don't see how doing this on an AREA frequency instead (I guess that would be equivalent to say LONDON INFORMATION which covers the whole of England practically) has any advantage?
(Note that England is a fraction of the size of the East Pilbara Shire in the NW of WA in which I once resided - not that its relevant, but still ...
)
Moreover, think how much safer the scenario you describe would be if both a/c were transponding Mode-C (at least) and if at least one of them had a TCAS display (can be included even with relatively cheap gear like GNS-430 these days). If such were common fit, then it would seem to make even less sense to to tie up an AREA frequency and other people's time hundred's of miles away with the transmissions you describe.
That's my thoughts anyway...
Andy