code review from Josh and Robert

@@ -30,28 +30,64 @@
 PARAMETERS
      name    A character string giving a name to the vmem arena to be created.
 
      base    An address indicating the lowest possible value in the arena.
 
-     size    The size of the arena to create
+     size    The size of the arena to create.
 
      quantum
              The arena's ``quantum''.  The granularity of the arena.  The
-             amount allocated at minimum by each request.
+             amount allocated at minimum by each request.  Must be a power of
+             2.
 
-     afunc   A function which is called to import new spans from source.
-             Which may be NULL if this arena does not import from another.
+     afunc   A function which is called to import new spans from source, which
+             may be NULL if this arena does not import from another.  When
+             calling vmem_create() afunc is an vmem_alloc_t a function taking
+             three parameters and returning a pointer to void (the imported
+             space):
 
-     ffunc   A function which is called to return spans to source.  Which may
-             be NULL if this arena does not import from another.
+             vmem_t *
+                     The source arena from which we'll import.  The source
+                     argument to vmem_create().
 
-     source  An arena from which this arena will import.  Which may be NULL if
+             size_t  The size to import
+
+             int     The vmflag argument used for the import.
+
+             When calling vmem_xcreate() afunc is an vmem_ximport_t a function
+             taking four parameters and returning a pointer to void (the
+             imported space):
+
+             vmem_t *
+                     The source arena from which we'll import.  The source
+                     argument to vmem_xcreate().
+
+             size_t *
+                     The size of the import, afunc may increase this size if
+                     that is desirable, but must never decrease it.
+
+             size_t  The desired alignment of the imported space.
+
+             int     the vmflag argument used for the import.
+
+     ffunc   A function which is called to return spans to source, which may
+             be NULL if this arena does not import from another.  This is a
+             vmem_free_t a function taking three parametes and returning void:
+
+             vmem_t  The arena to which space is being returned.  The source
+                     argument to vmem_create() or vmem_xcreate().
+
+             void *  The span being returned to the source arena.
+
+             size_t  The size of the span being returned to the source arena.
+
+     source  An arena from which this arena will import, which may be NULL if
              this arena does not import from another.
 
      qcache_max
              Each arena offers caching of integer multiples of quantum up to
-             qcache_max.
+             qcache_max, which may be 0.
 
      vmflag  A bitmask of flags indicating the characteristics of this arena.
 
              VMC_IDENTIFIER
                      The arena represents arbitrary integer identifiers,

@@ -67,17 +103,17 @@
 
      The afunc, ffunc, and source arguments combine to support a hierarchical
      structure of arenas, each importing from a single parent (the source).
      The vmem_create() and vmem_xcreate() functions differ in that the latter
      provides an interface for afunc to alter the size of the span imported
-     from source.  It is only legal to increase thise size.
+     from source.  It is only legal to increase this size.
 
 CONTEXT
      These functions can be called from user or kernel context.
 
 RETURN VALUES
-     Upon successful completion the vmem_create(and) vmem_xcreate() functions
+     Upon successful completion the vmem_create() and vmem_xcreate() functions
      return a pointer to a vmem arena.  Otherwise, NULL is returned to
      indicate the arena could not be created.
 
 SEE ALSO
      vmem(9), vmem_add(9F), vmem_alloc(9F)