[XeTeX] Whitespace in input

[Philip TAYLOR]

Herbert Schulz wrote:

>> "The latter" is what the TeXbok says (P.~39) : "Once a category code
>> has been attached to a character token, the attachment is permanent."
>>
>> ** Phil.

> What happens in a verbatim environment?

The verbatim environment sets up an environment within
which characters that have not yet been seen by TeX's
mouth receive category codes that potentially differ
from the category code that would normally be associated
with that character.  Once the category code has been
bound to a particular instance of that character, that
instance never changes its catcode.

** Phil.