Hi Ralph, > If study shows that old valid expressions can't be interpreted > differently under the new parsing rules, then fine. But I'd assume they > could be.
Why should they when they don't contain errors or use side effects? The current rules for numerical expressions and the conditional statement are very restricted, so the probability should be low that there are problems. I suggest to bring something from troff manual § 16 into § 1.4: N := c | 'string1'string2' | !N also regular expressions could be added: N := re'string'literal_string' And make & and : true AND and OR for any case. Then the condition in § 16 could just be .if N anything The overall syntax would not change. groff could *additional* implement that (Ex; expr) feature, but if the above doesn't cause problems it would also be a valuable improvement with minimum syntax changes (if it doesn't case problems with *correct* existing documents Heirloom would go that way). Carsten
