[evlatests] Terminology

[Barry Clark]

I'm starting to think about code to drive the 4 GHz samplers.  In order 
that the comments in my code bear some relation to what we eventually
end up calling things, I'd like to talk about terminology now.

My suggestion is that the first output from the T304s, be called
basebands A, B, C, D, as they are now, ignoring the fact that they
have different filters and samplers selected.

Let's call the second outputs from the T304s basebands E, F, G, H.

So the baseband pairs are AC, BD, EG, FH.

Another alternative is to assign nunbers to the baseband pairs, a la
AIPS, so the basebands become 1R, 1L, 2R, 2L, 3R, 3L, 4R, 4L.  (Which
T304 baseband 2R comes from TBD.)  I think this is more confusing 
because we seem to have settled on numbering the subbands, so subbands
would be things like 101R, 101L, 102R, 201R, etc. which I find less
euphonious than A01, C01, A02, B01, etc.