diff --git a/common/dtd/ldmlSupplemental.dtd b/common/dtd/ldmlSupplemental.dtd
index 97a7b9fd1c4..e53fe357614 100644
--- a/common/dtd/ldmlSupplemental.dtd
+++ b/common/dtd/ldmlSupplemental.dtd
@@ -275,7 +275,7 @@ CLDR data files are interpreted according to the LDML specification (http://unic
     <!--@MATCH:time/yyyy-MM-dd-->
     <!--@VALUE-->
 <!ATTLIST era code NMTOKEN #IMPLIED >
-    <!--@MATCH:regex/[a-z0-9]{3,8}(\-[a-z0-9]{3,8})*-->
+    <!--@MATCH:regex/[a-z0-9]{2,8}(\-[a-z0-9]{3,8})*-->
     <!--@VALUE-->
 <!ATTLIST era aliases NMTOKENS #IMPLIED >
     <!--@MATCH:set/regex/[a-z0-9]{2,8}(\-[a-z0-9]{3,8})*-->
diff --git a/common/supplemental/supplementalData.xml b/common/supplemental/supplementalData.xml
index ac22ab07718..8adaf798a08 100644
--- a/common/supplemental/supplementalData.xml
+++ b/common/supplemental/supplementalData.xml
@@ -4304,8 +4304,8 @@ XXX Code for transations where no currency is involved
         <calendar type="gregorian">
            <calendarSystem type="solar" />
            <eras>
-               <era type="0" end="0-12-31" code="gregory-inverse" aliases="bc bce"/>
-               <era type="1" start="1-01-01" code="gregory" aliases="ad ce"/>
+               <era type="0" end="0-12-31" code="bce" aliases="bc"/> <!-- Before Common Era, Before Christ -->
+               <era type="1" start="1-01-01" code="ce" aliases="ad"/> <!-- Common Era, Anno Domini -->
            </eras>
         </calendar>
         <calendar type="generic"/>
@@ -4557,96 +4557,96 @@ XXX Code for transations where no currency is involved
         <calendar type="islamic">
           <calendarSystem type="lunar" />
           <eras>
-              <era type="0" start="622-07-19" code="islamic" aliases="ah"/>
-              <era type="1" end="622-07-18" code="islamic-inverse" aliases="bh"/>
+              <era type="0" start="622-07-19" code="ah"/> <!-- Anno Hegirae -->
+              <era type="1" end="622-07-18" code="bh"/> <!-- Before Hijrah -->
           </eras>
         </calendar>
         <calendar type="islamic-civil">
           <calendarSystem type="lunar" />
           <eras>
-              <era type="0" start="622-07-19" code="islamic-civil" aliases="islamicc ah"/>
-              <era type="1" end="622-07-18" code="islamic-civil-inverse" aliases="bh"/>
+              <era type="0" start="622-07-19" code="ah"/> <!-- Anno Hegirae -->
+              <era type="1" end="622-07-18" code="bh"/> <!-- Before Hijrah -->
           </eras>
         </calendar>
         <calendar type="islamic-rgsa">
           <calendarSystem type="lunar" />
           <eras>
-              <era type="0" start="622-07-19" code="islamic-rgsa" aliases="ah"/>
-              <era type="1" end="622-07-18" code="islamic-rgsa-inverse" aliases="bh"/>
+              <era type="0" start="622-07-19" code="ah"/> <!-- Anno Hegirae -->
+              <era type="1" end="622-07-18" code="bh"/> <!-- Before Hijrah -->
           </eras>
         </calendar>
         <calendar type="islamic-tbla">
           <calendarSystem type="lunar" />
           <eras>
-              <era type="0" start="622-07-18" code="islamic-tbla" aliases="ah"/>
-              <era type="1" end="622-07-17" code="islamic-tbla-inverse" aliases="bh"/>
+              <era type="0" start="622-07-18" code="ah"/> <!-- Anno Hegirae -->
+              <era type="1" end="622-07-17" code="bh"/> <!-- Before Hijrah -->
           </eras>
         </calendar>
         <calendar type="islamic-umalqura">
           <calendarSystem type="lunar" />
           <eras>
-              <era type="0" start="622-07-19" code="islamic-umalqura" aliases="ah"/>
-              <era type="1" end="622-07-18" code="islamic-umalqura-inverse" aliases="bh"/>
+              <era type="0" start="622-07-19" code="ah"/> <!-- Anno Hegirae -->
+              <era type="1" end="622-07-18" code="bh"/> <!-- Before Hijrah -->
           </eras>
         </calendar>
         <calendar type="chinese">
           <calendarSystem type="lunisolar"/>
           <eras>
-              <era type="0" start="-2636-02-15" code="chinese"/> <!-- 'sequential' year -->
+              <era type="0" start="-2636-02-15"/> <!-- 'sequential' year -->
           </eras>
         </calendar>
         <calendar type="hebrew">
           <calendarSystem type="lunisolar"/>
           <eras>
-              <era type="0" start="-3760-09-07" code="hebrew" aliases="am"/>
+              <era type="0" start="-3760-09-07" code="am"/> <!-- Anno Mundi -->
           </eras>
         </calendar>
         <calendar type="buddhist">
           <calendarSystem type="solar" />
           <eras>
-              <era type="0" start="-542-01-01" code="buddhist" aliases="be"/>
+              <era type="0" start="-542-01-01" code="be"/> <!-- Buddhist Era -->
           </eras>
         </calendar>
         <calendar type="coptic">
           <calendarSystem type="other"/>
           <eras>
-              <era type="0" end="284-08-28" code="coptic-inverse"/>
-              <era type="1" start="284-08-29" code="coptic"/>
+              <era type="0" end="284-08-28" code="bd"/> <!-- Before Diocletian. NOTE: No evidence this era is used -->
+              <era type="1" start="284-08-29" code="am"/> <!-- Anno Martyrum -->
           </eras>
         </calendar>
         <calendar type="persian">
           <calendarSystem type="solar"/>
           <eras>
-              <era type="0" start="622-03-21" code="persian" aliases="ap"/>
+              <era type="0" start="622-03-21" code="ap"/> <!-- Anno Persico -->
           </eras>
         </calendar>
         <calendar type="dangi">
           <calendarSystem type="lunisolar"/>
           <eras>
-              <era type="0" start="-2332-02-15" code="dangi"/> <!-- 'sequential' year -->
+              <era type="0" start="-2332-02-15"/> <!-- 'sequential' year -->
           </eras>
         </calendar>
         <calendar type="ethiopic">
           <calendarSystem type="other"/>
           <eras>
-              <era type="0" start="-5492-07-17" code="ethioaa" aliases="ethiopic-amete-alem mundi"/>
-              <era type="1" start="8-08-27" code="ethiopic" aliases="incar"/>
+              <era type="0" start="-5492-07-17" code="aa"/> <!-- Amete Alem -->
+              <era type="1" start="8-08-27" code="am"/> <!-- Amete Mihret -->
           </eras>
         </calendar>
         <calendar type="ethiopic-amete-alem">
           <eras>
-              <era type="0" start="-5492-07-17" code="ethioaa" aliases="ethiopic-amete-alem mundi"/>
+              <era type="0" start="-5492-07-17" code="aa"/> <!-- Amete Alem -->
           </eras>
         </calendar>
         <calendar type="indian">
           <eras>
-              <era type="0" start="79-03-22" code="indian" aliases="saka"/>
+              <era type="0" start="79-03-22" code="shaka"/>
           </eras>
         </calendar>
         <calendar type="roc">
           <eras>
-              <era type="0" end="1911-12-31" code="roc-inverse" aliases="before-roc"/>
-              <era type="1" start="1912-01-01" code="roc" aliases="minguo"/>
+              <era type="0" end="1911-12-31" code="broc"/>
+              <era type="1" start="1912-01-01" code="roc"/>
           </eras>
         </calendar>