Update documentation to state there is three-value logic, not

three-value boolean logic.

Backpatch to 9.0.X since we just got another bug report about this
today.

diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
index 657835c701bc11a56e02cd0be6a008ff6c034d54..c1a34fb16986e0eff56bf22363e6dc88e5e2e6a3 100644 (file)
--- a/doc/src/sgml/func.sgml
+++ b/doc/src/sgml/func.sgml
@@ -82,8 +82,9 @@
      NOT
     
 
-    SQL uses a three-valued Boolean logic where the null value represents
-    unknown.  Observe the following truth tables:
+    SQL uses a three-valued logic system with true,
+    false, and null, which represents unknown.
+    Observe the following truth tables: