[texhax] Constructing a very thin space

[Philip Taylor]

Karl Berry wrote:

> I do not have an example at hand, but without the space after `em',
> TeX will still be reading and expanding tokens after the macro is
> called (to look for the <space> that's supposed to be there).

To look for the <space> that's supposed to be /where/, Karl ?

Considering \thinspace as an example, and using DEK's
definition from Plain.TeX :

\def\thinspace{\kern .16667em }

No space is expected after \thinspace, which is automatically
terminated by any non-letter; no space is expected after \kern .16667em,
since all 2-letter units are self-terminating and
there are no optional plus/minus modifiers, so I cannot see
to what "<space> that's supposed to be there" you are referring.

** Phil.