Branch Indirect on Condition. Instead of branching to the address pointed to by the second operand, it uses the second operand as the address of an 8 byte area which contains the address to which to branch. I guess this is sort of like an LG combined with a regular BCR. A nice way to implement branching via a branch table.
-- UNIX was not designed to stop you from doing stupid things, because that would also stop you from doing clever things. -- Doug Gwyn Maranatha! <>< John McKown
