SPARC assembly language question

[R. L. Welsh]

The Sun-4 Assembly Language Reference Manual (PN:800-1788-??) states (p. 12):

"All BiCC instructions may indicate that the annul bit is to be 
set by appending ',a' to the opcode; e.g. 'bgeu,a' ... "

What does setting the annul bit do and where can I get a better 
description of SPARC assembly language commands than this particular
document? 

	- Rikki	(UUCP: grebyn!macom1!rikki)