No apologies necessary - this is not my field - just dating the buildings from the wood is my area. Maybe I can get my nephew to chime in as he knows more about the practical aspects and terminology. I found a pretty good set of usages here:
http://www.wordnik.com/words/scantling/examplesAs for your question - there is no bracing below the trusses - none what so ever. There is a plaster cove supported by board scrap nailed however with split-board lath - that is what I tried to show in the drawing.
c b ais an @ da ko tacom . n et (no spaces)
