Clarify whether the standard readtable can be modified.

[yitzchak]

Section 2.1.1.2 states:

The standard readtable conforms to standard syntax. The consequences are undefined if an attempt is made to modify the standard readtable. To achieve the effect of altering or extending standard syntax, a copy of the standard readtable can be created; see the function copy-readtable.

And yet in the glossary:

standard readtable n. A readtable that is different from the initial readtable, that implements the expression syntax defined in this specification, and that, unlike other readtables, must never be modified by any program. (Although the definite reference “the standard readtable” is generally used within this document, it is actually implementation-dependent whether a single object fills the role of the standard readtable, or whether there might be multiple such objects, any one of which could be used on any given occasion where “the standard readtable” is called for. As such, this phrase should be seen as an indefinite reference in all cases except for anaphoric references.)

[Bike]

I don't think there's any standard way to actually get at the standard readtable anyway, so in practice it's less "must not" and more "can not"

[yitzchak]

(with-standard-io-syntax *readtable*) will return the standard readtable. You can do the same for the standard pprint dispatch table.