Fix cpointer and cstruct tag text

collects/scribblings/foreign/cpointer.scrbl

@@ -22,9 +22,10 @@ to Racket, and accept only such tagged pointers when going to C.  An
 optional @racket[ptr-type] can be given to be used as the base pointer
 type, instead of @racket[_pointer].
 
-By convention, tags should be symbols named after the
-type they point to.  For example, the cpointer @racket[_car] should
-be created using @racket['car] as the key.
+By convention, tags are symbols named after the
+type they point to.  For example, the cpointer @racket[_car] would
+be created using @racket['car] as the key. However, any symbol can be
+used as the tag.
 Pointer tags are checked with @racket[cpointer-has-tag?] and changed
 with @racket[cpointer-push-tag!] which means that other tags are
 preserved.  Specifically, if a base @racket[ptr-type] is given and is
@@ -46,7 +47,7 @@ are not tagged.}
                                  scheme-to-c-expr c-to-scheme-expr)]]{
 
 A macro version of @racket[_cpointer] and @racket[_cpointer/null],
-using the defined name for a tag string, and defining a predicate
+using the defined name for a tag symbol, and defining a predicate
 too. The @racket[_id] must start with @litchar{_}.
 
 The optional expressions produce optional arguments to @racket[_cpointer].
@@ -56,7 +57,7 @@ In addition to defining @racket[_id] to a type generated by
 type produced by @racket[_cpointer/null] type. Finally,
 @racketvarfont{id}@racketidfont{?}  is defined as a predicate, and
 @racketvarfont{id}@racketidfont{-tag} is defined as an accessor to
-obtain a tag. The tag is the string form of @racketvarfont{id}.}
+obtain a tag. The tag is the symbol form of @racketvarfont{id}.}
 
 @defproc*[([(cpointer-has-tag? [cptr any/c] [tag any/c]) boolean?]
            [(cpointer-push-tag! [cptr any/c] [tag any/c]) void])]{

collects/scribblings/foreign/types.scrbl

@@ -857,8 +857,10 @@ The resulting bindings are as follows:
 
  @item{@racketvarfont{id}@racketidfont{?}: a predicate for the new type.}
 
- @item{@racketvarfont{id}@racketidfont{-tag}: the tag string object that is
-  used with instances.}
+ @item{@racketvarfont{id}@racketidfont{-tag}: the tag object that is
+  used with instances.  The tag object may be the symbol form of 
+  @racketvarfont{id} or a list of symbols containing the @racketvarfont{id}
+  symbol and other symbols, such as the @racketvarfont[super-id] symbol.}
 
  @item{@racketidfont{make-}@racketvarfont{id} : a constructor, which expects
   an argument for each type.}
@@ -879,7 +881,8 @@ The resulting bindings are as follows:
 ]
 
 Objects of the new type are actually C pointers, with a type tag that
-is a list that contains the string form of @racketvarfont{id}.  Since
+is the symbol form of @racketvarfont{id} or a list that contains the 
+symbol form of @racketvarfont{id}.  Since
 structs are implemented as pointers, they can be used for a
 @racket[_pointer] input to a foreign function: their address will be
 used.  To make this a little safer, the corresponding cpointer type is