-.BR realloc (3)
-functions.
-.B xmalloc
-allocates a block of
-.I sz
-bytes and returns a pointer to the base of the block;
-.B xrealloc
-is given a pointer
-.I p
-to a block of memory, and returns the address of a new block of size
-.I sz
-bytes with the same contents as the original one (either truncated, if
-the new block is smaller, or padded with rubbish at the end if bigger).
+.BR x_free
+work with a given arena (see
+.BR arena (3)).
+.B x_alloc
+allocates a block of a given size;
+.B x_realloc
+resizes an allocated block;
+.B x_strdup
+allocates a copy of a null-terminated string; and
+.B x_free
+releases a block.
+.RB ( x_free
+is supplied for orthogonality's sake: it's equivalent to calling the
+.BR A_FREE (3)
+macro.)