[texhax] Some puzzling TeX (\@sptoken)

[Philip TAYLOR (Webmaster, Ret'd)]

Uwe Lueck wrote:
>
> "The quantity<space token>, which was used in the syntax of<optional
> spaces>  above, stands for an explicit or implicit space. In other words,
> it denotes either a character token of category 10, or a control sequence
> or active character whose current meaning has been made equal to such a
> token by \let or \futurelet."
>
> What seems *not to be said explicitly*, indeed!! (see
> announcement above), is that<one optional space>
> may be an implicit space token. (Of course it is said
> *implicitly*.)

So you would argue that although there is an explicit definition
of the sort of spaces that may form <optional spaces>, this does
not provide an explicit definition of the sort of spaces that may
form <one optional space>.  I am not sure I agree.

** Phil.