Day wrote:
> you want something that matches /^\D$/ as well as [A-Za-z0-9]+.

There's no \D in Treetop character classes, unlike Ruby regexps.

> but is my thinking clear, anyway?

Your thinking is clear, but Marco's isn't.

Marco, think about what you're asking. You want to match a
string of digits as a string, but also as a number. How is
Treetop supposed to know which? Is it that with a number,
the following character is not alphanumeric? If so, you must
tell Treetop that:

rule number
    [0-9.]+ & ![A-Za-z0-9.]
end

Clifford Heath.