diff --git a/doc/src/sgml/mvcc.sgml b/doc/src/sgml/mvcc.sgml
index 020bbcd0e2..49db3f176f 100644
--- a/doc/src/sgml/mvcc.sgml
+++ b/doc/src/sgml/mvcc.sgml
@@ -692,6 +692,8 @@ SELECT SUM(value) FROM mytab WHERE class = 2;
SHARE, SHARE ROW
EXCLUSIVE, EXCLUSIVE, and
ACCESS EXCLUSIVE lock modes.
+ This mode protects a table against concurrent data changes, and
+ is self-exclusive so that only one session can hold it at a time.
@@ -719,9 +721,8 @@ SELECT SUM(value) FROM mytab WHERE class = 2;
- This lock mode is not automatically acquired on user tables by any
- PostgreSQL command. However it is
- acquired on certain system catalogs in some operations.
+ This lock mode is not automatically acquired on tables by any
+ PostgreSQL command.