Ed was derived from Ken's earlier qed. Qed's descendant in Multics was described in a 1969 GE document: http://www.bitsavers.org/pdf/honeywell/multics/swenson/6906.multics-condens…. Unfortunately it describes regular expressions only sketchily by example. However, alternation, symbolized by | with grouping by parentheses, was supported in qed, whereas alternation was omitted from ed. The GE document does not mention character classes; an example shows how to use alternation for the same purpose. Beginning-of-line is specified by a logical-negation symbol. In apparent contradiction, the v1 manual says the meanings of [ and ^ are the same in ed and (an unspecified version of) qed. My guess about the discrepancies is no better than yours. (I am amused by the title "condensed guide" for a manual in which each qed request gets a full page of explanation. It exemplifies how Unix split from Multics in matters of taste.) Doug