diff --git a/Docs/src/callback.but b/Docs/src/callback.but
index abe57db0..fa69827d 100644
--- a/Docs/src/callback.but
+++ b/Docs/src/callback.but
@@ -100,6 +100,8 @@ Example:
 
 Called when the selection changes on the \R{pages}{component page}. Useful for using with \R{sectionsetflags}{SectionSetFlags} and \R{sectiongetflags}{SectionGetFlags}.
 
+Selection changes include both section selection and installation type change.
+
 \S3{onuserabort} .onUserAbort
 
 This callback is called when the user hits the 'cancel' button, and the install hasn't already failed. If this function calls \R{abort}{Abort}, the install will not be aborted.