diff --git a/src/backend/utils/adt/formatting.c b/src/backend/utils/adt/formatting.c
index a1145e2..ddafe9a 100644
--- a/src/backend/utils/adt/formatting.c
+++ b/src/backend/utils/adt/formatting.c
@@ -703,6 +703,7 @@ typedef enum
 	DCH_month,
 	DCH_mon,
 	DCH_ms,
+	DCH_of,
 	DCH_p_m,
 	DCH_pm,
 	DCH_q,
@@ -710,6 +711,8 @@ typedef enum
 	DCH_sssss,
 	DCH_ssss,
 	DCH_ss,
+	DCH_tzh,
+	DCH_tzm,
 	DCH_tz,
 	DCH_us,
 	DCH_ww,
@@ -866,6 +869,7 @@ static const KeyWord DCH_keywords[] = {
 	{"month", 5, DCH_month, false, FROM_CHAR_DATE_GREGORIAN},
 	{"mon", 3, DCH_mon, false, FROM_CHAR_DATE_GREGORIAN},
 	{"ms", 2, DCH_MS, true, FROM_CHAR_DATE_NONE},
+	{"of", 2, DCH_OF, false, FROM_CHAR_DATE_NONE},  /* o */
 	{"p.m.", 4, DCH_p_m, false, FROM_CHAR_DATE_NONE},	/* p */
 	{"pm", 2, DCH_pm, false, FROM_CHAR_DATE_NONE},
 	{"q", 1, DCH_Q, true, FROM_CHAR_DATE_NONE}, /* q */
@@ -873,6 +877,8 @@ static const KeyWord DCH_keywords[] = {
 	{"sssss", 5, DCH_SSSS, true, FROM_CHAR_DATE_NONE},	/* s */
 	{"ssss", 4, DCH_SSSS, true, FROM_CHAR_DATE_NONE},
 	{"ss", 2, DCH_SS, true, FROM_CHAR_DATE_NONE},
+	{"tzh", 3, DCH_TZH, false, FROM_CHAR_DATE_NONE},    /* t */
+	{"tzm", 3, DCH_TZM, true, FROM_CHAR_DATE_NONE},
 	{"tz", 2, DCH_tz, false, FROM_CHAR_DATE_NONE},	/* t */
 	{"us", 2, DCH_US, true, FROM_CHAR_DATE_NONE},	/* u */
 	{"ww", 2, DCH_WW, true, FROM_CHAR_DATE_GREGORIAN},	/* w */
@@ -955,7 +961,7 @@ static const int DCH_index[KeyWord_INDEX_SIZE] = {
 	DCH_P_M, DCH_Q, DCH_RM, DCH_SSSSS, DCH_TZH, DCH_US, -1, DCH_WW, -1, DCH_Y_YYY,
 	-1, -1, -1, -1, -1, -1, -1, DCH_a_d, DCH_b_c, DCH_cc,
 	DCH_day, -1, DCH_ff1, -1, DCH_hh24, DCH_iddd, DCH_j, -1, -1, DCH_mi,
-	-1, -1, DCH_p_m, DCH_q, DCH_rm, DCH_sssss, DCH_tz, DCH_us, -1, DCH_ww,
+	-1, DCH_of, DCH_p_m, DCH_q, DCH_rm, DCH_sssss, DCH_tzh, DCH_us, -1, DCH_ww,
 	-1, DCH_y_yyy, -1, -1, -1, -1
 
 	/*---- chars over 126 are skipped ----*/
diff --git a/src/test/regress/expected/timestamptz.out b/src/test/regress/expected/timestamptz.out
index 421ef25..2702e87 100644
--- a/src/test/regress/expected/timestamptz.out
+++ b/src/test/regress/expected/timestamptz.out
@@ -2161,6 +2161,71 @@ SELECT to_char(now(), 'OF') as "OF", to_char(now(), 'TZH:TZM') as "TZH:TZM";
 (1 row)
 
 RESET timezone;
+-- Check of, tzh, tzm with various zone offsets.
+SET timezone = '00:00';
+SELECT to_char(now(), 'of') as "of", to_char(now(), 'tzh:tzm') as "tzh:tzm";
+ of  | tzh:tzm 
+-----+---------
+ +00 | +00:00
+(1 row)
+
+SET timezone = '+02:00';
+SELECT to_char(now(), 'of') as "of", to_char(now(), 'tzh:tzm') as "tzh:tzm";
+ of  | tzh:tzm 
+-----+---------
+ -02 | -02:00
+(1 row)
+
+SET timezone = '-13:00';
+SELECT to_char(now(), 'of') as "of", to_char(now(), 'tzh:tzm') as "tzh:tzm";
+ of  | tzh:tzm 
+-----+---------
+ +13 | +13:00
+(1 row)
+
+SET timezone = '-00:30';
+SELECT to_char(now(), 'of') as "of", to_char(now(), 'tzh:tzm') as "tzh:tzm";
+   of   | tzh:tzm 
+--------+---------
+ +00:30 | +00:30
+(1 row)
+
+SET timezone = '00:30';
+SELECT to_char(now(), 'of') as "of", to_char(now(), 'tzh:tzm') as "tzh:tzm";
+   of   | tzh:tzm 
+--------+---------
+ -00:30 | -00:30
+(1 row)
+
+SET timezone = '-04:30';
+SELECT to_char(now(), 'of') as "of", to_char(now(), 'tzh:tzm') as "tzh:tzm";
+   of   | tzh:tzm 
+--------+---------
+ +04:30 | +04:30
+(1 row)
+
+SET timezone = '04:30';
+SELECT to_char(now(), 'of') as "of", to_char(now(), 'tzh:tzm') as "tzh:tzm";
+   of   | tzh:tzm 
+--------+---------
+ -04:30 | -04:30
+(1 row)
+
+SET timezone = '-04:15';
+SELECT to_char(now(), 'of') as "of", to_char(now(), 'tzh:tzm') as "tzh:tzm";
+   of   | tzh:tzm 
+--------+---------
+ +04:15 | +04:15
+(1 row)
+
+SET timezone = '04:15';
+SELECT to_char(now(), 'of') as "of", to_char(now(), 'tzh:tzm') as "tzh:tzm";
+   of   | tzh:tzm 
+--------+---------
+ -04:15 | -04:15
+(1 row)
+
+RESET timezone;
 CREATE TABLE TIMESTAMPTZ_TST (a int , b timestamptz);
 -- Test year field value with len > 4
 INSERT INTO TIMESTAMPTZ_TST VALUES(1, 'Sat Mar 12 23:58:48 1000 IST');
diff --git a/src/test/regress/sql/timestamptz.sql b/src/test/regress/sql/timestamptz.sql
index 17ced99..f7664e2 100644
--- a/src/test/regress/sql/timestamptz.sql
+++ b/src/test/regress/sql/timestamptz.sql
@@ -354,6 +354,27 @@ SET timezone = '04:15';
 SELECT to_char(now(), 'OF') as "OF", to_char(now(), 'TZH:TZM') as "TZH:TZM";
 RESET timezone;
 
+-- Check of, tzh, tzm with various zone offsets.
+SET timezone = '00:00';
+SELECT to_char(now(), 'of') as "of", to_char(now(), 'tzh:tzm') as "tzh:tzm";
+SET timezone = '+02:00';
+SELECT to_char(now(), 'of') as "of", to_char(now(), 'tzh:tzm') as "tzh:tzm";
+SET timezone = '-13:00';
+SELECT to_char(now(), 'of') as "of", to_char(now(), 'tzh:tzm') as "tzh:tzm";
+SET timezone = '-00:30';
+SELECT to_char(now(), 'of') as "of", to_char(now(), 'tzh:tzm') as "tzh:tzm";
+SET timezone = '00:30';
+SELECT to_char(now(), 'of') as "of", to_char(now(), 'tzh:tzm') as "tzh:tzm";
+SET timezone = '-04:30';
+SELECT to_char(now(), 'of') as "of", to_char(now(), 'tzh:tzm') as "tzh:tzm";
+SET timezone = '04:30';
+SELECT to_char(now(), 'of') as "of", to_char(now(), 'tzh:tzm') as "tzh:tzm";
+SET timezone = '-04:15';
+SELECT to_char(now(), 'of') as "of", to_char(now(), 'tzh:tzm') as "tzh:tzm";
+SET timezone = '04:15';
+SELECT to_char(now(), 'of') as "of", to_char(now(), 'tzh:tzm') as "tzh:tzm";
+RESET timezone;
+
 CREATE TABLE TIMESTAMPTZ_TST (a int , b timestamptz);
 
 -- Test year field value with len > 4