diff --git a/icu4c/source/data/mappings/ibm-1390_P110-2003.ucm b/icu4c/source/data/mappings/ibm-1390_P110-2003.ucm
index dc1feb926f2..533f4ee3284 100644
--- a/icu4c/source/data/mappings/ibm-1390_P110-2003.ucm
+++ b/icu4c/source/data/mappings/ibm-1390_P110-2003.ucm
@@ -61,7 +61,6 @@ CHARMAP
 <U0021> \x5A |0
 <U0022> \x7F |0
 <U0023> \x7B |0
-<U0024> \xE0 |0
 <U0025> \x6C |0
 <U0026> \x50 |0
 <U0027> \x7D |0
@@ -116,42 +115,12 @@ CHARMAP
 <U0058> \xE7 |0
 <U0059> \xE8 |0
 <U005A> \xE9 |0
-<U005B> \x70 |0
-<U005C> \xB2 |0
-<U005D> \x80 |0
 <U005E> \xB0 |0
 <U005F> \x6D |0
 <U0060> \x79 |0
-<U0061> \x62 |0
-<U0062> \x63 |0
-<U0063> \x64 |0
-<U0064> \x65 |0
-<U0065> \x66 |0
-<U0066> \x67 |0
-<U0067> \x68 |0
-<U0068> \x69 |0
-<U0069> \x71 |0
-<U006A> \x72 |0
-<U006B> \x73 |0
-<U006C> \x74 |0
-<U006D> \x75 |0
-<U006E> \x76 |0
-<U006F> \x77 |0
-<U0070> \x78 |0
-<U0071> \x8B |0
-<U0072> \x9B |0
-<U0073> \xAB |0
-<U0074> \xB3 |0
-<U0075> \xB4 |0
-<U0076> \xB5 |0
-<U0077> \xB6 |0
-<U0078> \xB7 |0
-<U0079> \xB8 |0
-<U007A> \xB9 |0
 <U007B> \xC0 |0
 <U007C> \x4F |0
 <U007D> \xD0 |0
-<U007E> \xA0 |0
 <U007F> \x07 |0
 <U0080> \x20 |0
 <U0081> \x21 |0
@@ -187,10 +156,7 @@ CHARMAP
 <U009F> \xFF |0
 <U00A0> \xD6\x41 |0
 <U00A1> \xD6\x42 |0
-<U00A2> \xB1 |0
-<U00A3> \x4A |0
 <U00A4> \xD6\x43 |0
-<U00A5> \x5B |0
 <U00A6> \x42\x6A |0
 <U00A7> \x44\x6A |0
 <U00A8> \x44\x60 |0
@@ -957,7 +923,6 @@ CHARMAP
 <U203B> \x44\x6B |0
 <U203C> \xDD\xD0 |0
 <U203D> \xDD\xD1 |0
-<U203E> \xA1 |0
 <U203F> \xDD\xD2 |0
 <U2040> \xDD\xD3 |0
 <U2041> \xDD\xD4 |0
@@ -1009,8 +974,6 @@ CHARMAP
 <U20A8> \xDE\x7F |0
 <U20A9> \xDE\x80 |0
 <U20AA> \xDE\x81 |0
-<U20AC> \xE1 |0
-<U20AC> \x42\xE1 |3
 <U2100> \xDE\xA7 |0
 <U2101> \xDE\xA8 |0
 <U2102> \xDE\xA9 |0
@@ -21945,67 +21908,8 @@ CHARMAP
 <UFF5E> \xE9\xF4 |0
 <UFF5F> \xE9\xF7 |0
 <UFF60> \xE9\xF8 |0
-<UFF61> \x41 |0
-<UFF62> \x42 |0
-<UFF63> \x43 |0
-<UFF64> \x44 |0
-<UFF65> \x45 |0
-<UFF66> \x46 |0
-<UFF67> \x47 |0
-<UFF68> \x48 |0
-<UFF69> \x49 |0
-<UFF6A> \x51 |0
-<UFF6B> \x52 |0
-<UFF6C> \x53 |0
-<UFF6D> \x54 |0
-<UFF6E> \x55 |0
-<UFF6F> \x56 |0
 <UFF70> \x58 |0
-<UFF71> \x81 |0
-<UFF72> \x82 |0
-<UFF73> \x83 |0
-<UFF74> \x84 |0
-<UFF75> \x85 |0
-<UFF76> \x86 |0
-<UFF77> \x87 |0
-<UFF78> \x88 |0
-<UFF79> \x89 |0
-<UFF7A> \x8A |0
-<UFF7B> \x8C |0
-<UFF7C> \x8D |0
-<UFF7D> \x8E |0
-<UFF7E> \x8F |0
-<UFF7F> \x90 |0
-<UFF80> \x91 |0
-<UFF81> \x92 |0
-<UFF82> \x93 |0
-<UFF83> \x94 |0
-<UFF84> \x95 |0
-<UFF85> \x96 |0
-<UFF86> \x97 |0
-<UFF87> \x98 |0
-<UFF88> \x99 |0
 <UFF89> \x9A |0
-<UFF8A> \x9D |0
-<UFF8B> \x9E |0
-<UFF8C> \x9F |0
-<UFF8D> \xA2 |0
-<UFF8E> \xA3 |0
-<UFF8F> \xA4 |0
-<UFF90> \xA5 |0
-<UFF91> \xA6 |0
-<UFF92> \xA7 |0
-<UFF93> \xA8 |0
-<UFF94> \xA9 |0
-<UFF95> \xAA |0
-<UFF96> \xAC |0
-<UFF97> \xAD |0
-<UFF98> \xAE |0
-<UFF99> \xAF |0
-<UFF9A> \xBA |0
-<UFF9B> \xBB |0
-<UFF9C> \xBC |0
-<UFF9D> \xBD |0
 <UFF9E> \xBE |0
 <UFF9F> \xBF |0
 <UFFE0> \x43\x4A |0
@@ -22322,6 +22226,40 @@ END CHARMAP
 CHARMAP
 <U000E> \x3F |2
 <U000F> \x3F |2
+<U0024> \xE0 |0
+<U005B> \x70 |0
+<U005C> \xB2 |0
+<U005D> \x80 |0
+<U0061> \x62 |0
+<U0062> \x63 |0
+<U0063> \x64 |0
+<U0064> \x65 |0
+<U0065> \x66 |0
+<U0066> \x67 |0
+<U0067> \x68 |0
+<U0068> \x69 |0
+<U0069> \x71 |0
+<U006A> \x72 |0
+<U006B> \x73 |0
+<U006C> \x74 |0
+<U006D> \x75 |0
+<U006E> \x76 |0
+<U006F> \x77 |0
+<U0070> \x78 |0
+<U0071> \x8B |0
+<U0072> \x9B |0
+<U0073> \xAB |0
+<U0074> \xB3 |0
+<U0075> \xB4 |0
+<U0076> \xB5 |0
+<U0077> \xB6 |0
+<U0078> \xB7 |0
+<U0079> \xB8 |0
+<U007A> \xB9 |0
+<U007E> \xA0 |0
+<U00A2> \xB1 |0
+<U00A3> \x4A |0
+<U00A5> \x5B |0
 <U00E6> \xD6\x7B |0
 <U00E6><U0300> \xEC\xC3 |0
 <U0254> \xD8\x90 |0
@@ -22340,6 +22278,9 @@ CHARMAP
 <U02E5><U02E9> \xEC\xCD |0
 <U02E9> \xD9\x46 |0
 <U02E9><U02E5> \xEC\xCC |0
+<U203E> \xA1 |0
+<U20AC> \xE1 |0
+<U20AC> \x42\xE1 |3
 <U303F> \x3F |2
 <U304B> \x44\x86 |0
 <U304B><U309A> \xEC\xB5 |0
@@ -22369,6 +22310,65 @@ CHARMAP
 <U30C8><U309A> \xEC\xC1 |0
 <U31F7> \xEC\x8C |0
 <U31F7><U309A> \xEC\xC2 |0
+<UFF61> \x41 |0
+<UFF62> \x42 |0
+<UFF63> \x43 |0
+<UFF64> \x44 |0
+<UFF65> \x45 |0
+<UFF66> \x46 |0
+<UFF67> \x47 |0
+<UFF68> \x48 |0
+<UFF69> \x49 |0
+<UFF6A> \x51 |0
+<UFF6B> \x52 |0
+<UFF6C> \x53 |0
+<UFF6D> \x54 |0
+<UFF6E> \x55 |0
+<UFF6F> \x56 |0
+<UFF71> \x81 |0
+<UFF72> \x82 |0
+<UFF73> \x83 |0
+<UFF74> \x84 |0
+<UFF75> \x85 |0
+<UFF76> \x86 |0
+<UFF77> \x87 |0
+<UFF78> \x88 |0
+<UFF79> \x89 |0
+<UFF7A> \x8A |0
+<UFF7B> \x8C |0
+<UFF7C> \x8D |0
+<UFF7D> \x8E |0
+<UFF7E> \x8F |0
+<UFF7F> \x90 |0
+<UFF80> \x91 |0
+<UFF81> \x92 |0
+<UFF82> \x93 |0
+<UFF83> \x94 |0
+<UFF84> \x95 |0
+<UFF85> \x96 |0
+<UFF86> \x97 |0
+<UFF87> \x98 |0
+<UFF88> \x99 |0
+<UFF8A> \x9D |0
+<UFF8B> \x9E |0
+<UFF8C> \x9F |0
+<UFF8D> \xA2 |0
+<UFF8E> \xA3 |0
+<UFF8F> \xA4 |0
+<UFF90> \xA5 |0
+<UFF91> \xA6 |0
+<UFF92> \xA7 |0
+<UFF93> \xA8 |0
+<UFF94> \xA9 |0
+<UFF95> \xAA |0
+<UFF96> \xAC |0
+<UFF97> \xAD |0
+<UFF98> \xAE |0
+<UFF99> \xAF |0
+<UFF9A> \xBA |0
+<UFF9B> \xBB |0
+<UFF9C> \xBC |0
+<UFF9D> \xBD |0
 <UFFE8> \x3F |2
 <UFFE9> \x3F |2
 <UFFEA> \x3F |2
diff --git a/icu4c/source/data/mappings/ibm-1399_P110-2003.ucm b/icu4c/source/data/mappings/ibm-1399_P110-2003.ucm
index de02c1733fe..43ea0c0ab9e 100644
--- a/icu4c/source/data/mappings/ibm-1399_P110-2003.ucm
+++ b/icu4c/source/data/mappings/ibm-1399_P110-2003.ucm
@@ -26,6 +26,10 @@
 <icu:state>                   0-ff:1.i
 <icu:state>                   0-40:1.i, 41-fe:1.p, ff:1.i
 
+# build an extension-only (delta) .cnv file
+# requires the base .cnv file at runtime
+<icu:base>                    "ibm-1390_P110-2003"
+
 CHARMAP
 <U0000> \x00 |0
 <U0001> \x01 |0
diff --git a/icu4c/source/data/mappings/ibm-16684_P110-2003.ucm b/icu4c/source/data/mappings/ibm-16684_P110-2003.ucm
index 766496cb890..8b94cc6a99a 100644
--- a/icu4c/source/data/mappings/ibm-16684_P110-2003.ucm
+++ b/icu4c/source/data/mappings/ibm-16684_P110-2003.ucm
@@ -24,6 +24,10 @@
 <icu:state>                   
 <icu:state>                   41-fe.p
 
+# build an extension-only (delta) .cnv file
+# requires the base .cnv file at runtime
+<icu:base>                    "ibm-1390_P110-2003"
+
 CHARMAP
 <U00A0> \xD6\x41 |0
 <U00A1> \xD6\x42 |0