Include keywords from CASE implementation.

Rearrange a few other keywords to put them in the proper category.

doc/src/sgml/syntax.sgml

@@ -73,12 +73,15 @@ or <acronym>SQL3</acronym> reserved words, and which
 are allowed to be present as column labels, but not as identifiers:
 
 <programlisting>
-CROSS CURRENT 
+CASE COALESCE CROSS CURRENT 
+ELSE END
 FALSE FOREIGN 
 GROUP 
+NULLIF
 ORDER 
 POSITION PRECISION 
-TABLE TRANSACTION TRUE
+TABLE THEN TRANSACTION TRUE
+WHEN
 </programlisting>
 
 The following are <productname>Postgres</productname>
@@ -88,11 +91,12 @@ or <acronym>SQL3</acronym> reserved words:
 <programlisting>
 ADD ALL ALTER AND ANY AS ASC
 BEGIN BETWEEN BOTH BY
-CASCADE CAST CHAR CHARACTER CHECK CLOSE COLLATE COLUMN COMMIT 
-CONSTRAINT CREATE CURRENT_DATE CURRENT_TIME 
-CURRENT_TIMESTAMP CURRENT_USER CURSOR
+CASCADE CAST CHAR CHARACTER CHECK CLOSE 
+ COLLATE COLUMN COMMIT CONSTRAINT 
+ CREATE CURRENT_DATE CURRENT_TIME 
+ CURRENT_TIMESTAMP CURRENT_USER CURSOR
 DECIMAL DECLARE DEFAULT DELETE DESC DISTINCT DROP
-END EXECUTE EXISTS EXTRACT
+EXECUTE EXISTS EXTRACT
 FETCH FLOAT FOR FROM FULL
 GRANT 
 HAVING
@@ -122,7 +126,7 @@ CHAR_LENGTH CHARACTER_LENGTH
 The following are <acronym>SQL92</acronym> or <acronym>SQL3</acronym> 
 reserved key words which
 are not <productname>Postgres</productname> reserved key words, but
-if used as type names which are always translated into an alternate, native type:
+if used as type names are always translated into an alternate, native type:
 
 <programlisting>
 BOOLEAN DOUBLE FLOAT INT INTEGER INTERVAL REAL SMALLINT
@@ -147,25 +151,24 @@ in other contexts.
 <programlisting>
 ALLOCATE ARE ASSERTION AT AUTHORIZATION AVG 
 BIT BIT_LENGTH
-CASCADED CASE CATALOG COALESCE COLLATION
-CONNECT CONNECTION CONSTRAINTS CONTINUE CONVERT CORRESPONDING COUNT
+CASCADED CATALOG COLLATION CONNECT CONNECTION
+ CONSTRAINTS CONTINUE CONVERT CORRESPONDING COUNT
 DATE DEALLOCATE DEC DESCRIBE DESCRIPTOR DIAGNOSTICS DISCONNECT DOMAIN 
-ELSE END-EXEC ESCAPE EXCEPT EXCEPTION EXEC EXTERNAL 
+END-EXEC ESCAPE EXCEPT EXCEPTION EXEC EXTERNAL 
 FIRST FOUND
 GET GLOBAL GO GOTO 
 IDENTITY IMMEDIATE INDICATOR INITIALLY INPUT INTERSECT ISOLATION 
 LAST LEVEL LOWER 
 MAX MIN MODULE 
-NULLIF
 OCTET_LENGTH OPEN OUTPUT OVERLAPS 
 PREPARE PRESERVE 
 RESTRICT ROWS
 SCHEMA SECTION SESSION SESSION_USER SIZE SOME 
-SQL SQLCODE SQLERROR SQLSTATE SUM SYSTEM_USER
-TEMPORARY THEN TRANSLATE TRANSLATION 
+ SQL SQLCODE SQLERROR SQLSTATE SUM SYSTEM_USER
+TEMPORARY TRANSLATE TRANSLATION 
 UNKNOWN UPPER USAGE
 VALUE 
-WHEN WHENEVER WRITE
+WHENEVER WRITE
 </programlisting>
 
 <Sect2>