Thanks, Captain Fathom...
I did eventually manage to find the answer (I just wasn't looking hard enough in our Maintenance Manual)...
31-41-00
"Takeoff/Go-Around Mode
1) When the thrust management computer is in either the takeoff or go-around mode, the yellow band exceedance operations for EGT are inhibited for five minutes. Automatic secondary data initiation does not occur until the red band area is entered"
Secondary data, I presume, is that on the Lower EICAS... EGT is on the Upper EICAS.... so now I'm not sure if the other parameter yellow band stuff is also inhibited
Rgds.
NSEU.