Re: eqn anomaly

[Tadziu Hoffmann]

> As far as I can tell from Kernighan and Cherry[1], eqn's "define"s
> aren't parameterized at all.  The groff eqn(1) man page claims to
> document (only) extensions to classical eqn, but I don't see this
> extension described there.

It actually does: in subsection "Macros":

   Macros

      Macros can take arguments.  In a macro body, $n where
      n is between 1 and 9, is replaced by the nth argument
      if the macro is called with arguments; if there are
      fewer than n arguments, it is replaced by nothing.
      A word containing a left parenthesis where the part
      of the word before the left parenthesis  has  been
      defined  using  the define command is recognized as a
      macro call with arguments; characters following the
      left parenthesis up to a matching right parenthesis
      are treated as comma-separated arguments; commas inside
      nested parentheses do not terminate an argument.


So it does mention grouping with parentheses being understood,
but it says nothing about understanding "strings" delimited by
quotes.