diff --git a/Code/TODO.text b/Code/TODO.text
index ce2ded5..ac02040 100644
--- a/Code/TODO.text
+++ b/Code/TODO.text
@@ -71,6 +71,6 @@ cdmt set-difference
 cdmt nset-difference
 cdmt set-exclusive-or
 cdmt nset-exclusive-or
-c_mt subsetp
+cdmt subsetp
 cdmt union
 cdmt nunion
diff --git a/Code/subsetp.lisp b/Code/subsetp.lisp
index d7a0497..2278ad8 100644
--- a/Code/subsetp.lisp
+++ b/Code/subsetp.lisp
@@ -50,3 +50,18 @@
        key key-supplied-p
        test test-supplied-p
        test-not test-not-supplied-p))))
+
+(setf (documentation 'subsetp 'function)
+      (format nil
+              "Syntax: subsetp list-1 list-2 &key key test test-not~@
+               ~%~a~%~%~a~%~%~a~%~%~a~%~@
+               Either TEST or TEST-NOT is applied to the result of~@
+               applying KEY to an element of LIST-1 and and the result~@
+               of applying KEY to an element of LIST-2 in that order.~@
+               If for every element E1 of LIST-1, there is an element E2~@
+               of LIST-2 such that E1 and E2 satisfy the test, then this~@
+               function returns true.  Otherwise, it returns false."
+              *list-1-and-list-2-must-be-proper*
+              *key*
+              *key-applied-to-elements-of-list-1-and-list-1*
+              *test-and-test-not*))