diff -r e520f0f4b1cf -r d0a758e7002b mercurial/help/revisions.txt
--- a/mercurial/help/revisions.txt	Wed Jan 11 11:37:38 2017 -0800
+++ b/mercurial/help/revisions.txt	Wed Jan 11 22:46:07 2017 -0800
@@ -33,7 +33,7 @@
 =============================
 
 Mercurial supports a functional language for selecting a set of
-revisions.
+revisions. Expressions in this language are called revsets.
 
 The language supports a number of predicates which are joined by infix
 operators. Parenthesis can be used for grouping.