I was just about to report on my results, after a tiny bit of digging, which included this. The important datum is that PAL-11 (in DEC-11-GGPB-D, "paper tape software", April 1970, revised March 1971), which _preceded_ Macro-11, _does not_ include .ASCIZ (although it has .ASCII). My oldest Macro-11 book (DEC-11-OMACA-B-D, "BATCH-11/DOS-11 Assembler (MACRO-11)", April 1972, revised March 1973) does have .ASCIZ. So in the DEC PDP-11 universe, it dates from sometime between 1970 and 1972. I'm not sure if Bell had any of the DEC paper tape software: "In early 1970 we proposed acquisition of a PDP-11, which had just been introduced by Digital. ... an order for a PDP-11 was placed in May. The processor arrived at the end of the summer, but the PDP-11 was so new a product that no disk was available until December. In the meantime, a rudimentary, core-only version of Unix was written using a cross-assembler on the PDP-7." So the .ASCIZ in Macro-11 wasn't until a couple of years later. Noel