I may be mistaken, but I do recall that IEFSD095 - the code that produced the Block letters for printout separator pages - used the same register for the operands in a BXLE??BXH to generate the block letters from a bit map coded inline. I also recall a rumour from someone who had found the source code that there were at least 2 pages of comments explaining the instruction operation.
But it was a looooong time ago, and I may have "misremembered". Perhaps someone with access to the OS/360 source (Hercules project?) may be able to confirm/deny/modify. All corrections welcome, if only to repair crusty brain cells! Mike Kerford-Byrnes
