diff --git a/spec/registry.dtd b/spec/registry.dtd
index 312bd4008..8abbbc6e6 100644
--- a/spec/registry.dtd
+++ b/spec/registry.dtd
@@ -1,11 +1,17 @@
 <!ELEMENT registry (function|validationRule)*>
+<!ATTLIST registry
+    xml:lang       NMTOKEN  #IMPLIED
+>
 
-<!ELEMENT function (description,(formatSignature|matchSignature|alias)+)>
+<!ELEMENT function (description+,(formatSignature|matchSignature|alias)+)>
 <!ATTLIST function
     name           NMTOKEN  #REQUIRED
 >
 
 <!ELEMENT description (#PCDATA)>
+<!ATTLIST description
+    xml:lang       NMTOKEN  #IMPLIED
+>
 
 <!ELEMENT validationRule EMPTY>
 <!ATTLIST validationRule
@@ -20,14 +26,14 @@
 
 <!ELEMENT matchSignature (input?,option*,match*,override*)>
 
-<!ELEMENT input EMPTY>
+<!ELEMENT input (description*)>
 <!ATTLIST input
     values         NMTOKENS      #IMPLIED
     validationRule IDREF         #IMPLIED
     readonly       (true|false)  "false"
 >
 
-<!ELEMENT option EMPTY>
+<!ELEMENT option (description*)>
 <!ATTLIST option
     name           NMTOKEN       #REQUIRED
     values         NMTOKENS      #IMPLIED
diff --git a/spec/registry.md b/spec/registry.md
index e191b052f..bcf00ff8f 100644
--- a/spec/registry.md
+++ b/spec/registry.md
@@ -32,7 +32,7 @@ The registry contains descriptions of function signatures.
 
 The main building block of the registry is the `<function>` element.
 It represents an implementation of a custom function available to translation at runtime.
-A function defines a human-readable _description_ of its behavior
+A function defines a human-readable `<description>` of its behavior
 and one or more machine-readable _signatures_ of how to call it.
 Named `<validationRule>` elements can optionally define regex validation rules for
 literals, option values, and variant keys.
@@ -74,6 +74,11 @@ which provide shorthands for commonly used option baskets.
 An _alias name_ may be used equivalently to a _function name_ in messages.
 Its `<setOption>` values are always set, and may not be overridden in message annotations.
 
+If a `<function>`, `<input>` or `<option>` includes multiple `<description>` elements,
+each SHOULD have a different `xml:lang` attribute value.
+This allows for the descriptions of these elements to be themselves localized
+according to the preferred locale of the message authors and editors.
+
 ## Example
 
 The following `registry.xml` is an example of a registry file
@@ -84,7 +89,7 @@ For the sake of brevity, only `locales="en"` is considered.
 <?xml version="1.0" encoding="UTF-8" ?>
 <!DOCTYPE registry SYSTEM "./registry.dtd">
 
-<registry>
+<registry xml:lang="en">
     <function name="platform">
         <description>Match the current OS.</description>
         <matchSignature>
@@ -165,7 +170,7 @@ A localization engineer can then extend the registry by defining the following `
 <?xml version="1.0" encoding="UTF-8" ?>
 <!DOCTYPE registry SYSTEM "./registry.dtd">
 
-<registry>
+<registry xml:lang="en">
     <function name="noun">
         <description>Handle the grammar of a noun.</description>
         <formatSignature>
diff --git a/spec/registry.xml b/spec/registry.xml
index baff8025e..25fff3695 100644
--- a/spec/registry.xml
+++ b/spec/registry.xml
@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <?xml-model href="registry.dtd" type="application/xml-dtd"?>
-<registry>
+<registry xml:lang="en">
   <!-- All regex here are to be seen as provisory. See issue #422. -->
   <validationRule id="anyNumber" regex="-?(0|([1-9]\d*))(\.\d*)?([eE][-+]?\d+)?"/>
   <validationRule id="positiveInteger" regex="0|([1-9]\d*)"/>
@@ -11,25 +11,41 @@
 
   <function name="datetime">
     <!-- https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl/DateTimeFormat/DateTimeFormat -->
-    <description>Locale-sensitive date and time formatting</description>
+    <description>
+      Locale-sensitive date and time formatting
+    </description>
 
     <formatSignature>
       <input validationRule="iso8601"/>
-      <!-- The predefined date formatting style to use. -->
-      <option name="dateStyle" values="full long medium short"/>
-      <!-- The predefined time formatting style to use. -->
-      <option name="timeStyle" values="full long medium short"/>
-      <!-- Calendar to use. -->
-      <option name="calendar" values="buddhist chinese coptic dangi ethioaa ethiopic gregory hebrew indian islamic islamic-umalqura islamic-tbla islamic-civil islamic-rgsa iso8601 japanese persian roc"/>
-      <!-- Numbering system to use. -->
-      <option name="numberingSystem" values="arab arabext bali beng deva fullwide gujr guru hanidec khmr knda laoo latn limb mlym mong mymr orya tamldec telu thai tibt"/>
-      <!-- The time zone to use. The only value implementations must recognize
-         is "UTC"; the default is the runtime's default time zone.
-         Implementations may also recognize the time zone names of the IANA
-         time zone database, such as "Asia/Shanghai", "Asia/Kolkata",
-         "America/New_York".
-      -->
-      <option name="timeZone" validationRule="timeZoneId"/>
+      <option name="dateStyle" values="full long medium short">
+        <description>
+          The predefined date formatting style to use.
+        </description>
+      </option>
+      <option name="timeStyle" values="full long medium short">
+        <description>
+          The predefined time formatting style to use.
+        </description>
+      </option>
+      <option name="calendar" values="buddhist chinese coptic dangi ethioaa ethiopic gregory hebrew indian islamic islamic-umalqura islamic-tbla islamic-civil islamic-rgsa iso8601 japanese persian roc">
+        <description>
+          Calendar to use.
+        </description>
+      </option>
+      <option name="numberingSystem" values="arab arabext bali beng deva fullwide gujr guru hanidec khmr knda laoo latn limb mlym mong mymr orya tamldec telu thai tibt">
+        <description>
+          Numbering system to use.
+        </description>
+      </option>
+      <option name="timeZone" validationRule="timeZoneId">
+        <description>
+          The time zone to use.
+          The only value implementations must recognize is "UTC";
+          the default is the runtime's default time zone.
+          Implementations may also recognize the time zone names of the IANA time zone database,
+          such as "Asia/Shanghai", "Asia/Kolkata", "America/New_York".
+        </description>
+      </option>
     </formatSignature>
 
     <!-- TODO: clarify if this is OK or if it is an abuse.
@@ -38,108 +54,193 @@
     -->
     <formatSignature>
       <input validationRule="iso8601"/>
-      <!-- Calendar to use. -->
-      <option name="calendar" values="buddhist chinese coptic dangi ethioaa ethiopic gregory hebrew indian islamic islamic-umalqura islamic-tbla islamic-civil islamic-rgsa iso8601 japanese persian roc"/>
-      <!-- The formatting style used for day periods like "in the morning", "am", "noon", "n" etc. -->
-      <option name="dayPeriod" values="narrow short long"/>
-      <!-- Numbering system to use. -->
-      <option name="numberingSystem" values="arab arabext bali beng deva fullwide gujr guru hanidec khmr knda laoo latn limb mlym mong mymr orya tamldec telu thai tibt"/>
-      <!-- The time zone to use. The only value implementations must recognize
-         is "UTC"; the default is the runtime's default time zone.
-         Implementations may also recognize the time zone names of the IANA time zone
-         database, such as "Asia/Shanghai", "Asia/Kolkata", "America/New_York".
-      -->
-      <option name="timeZone" validationRule="timeZoneId"/>
-      <!-- The hour cycle to use. -->
-      <option name="hourCycle" values="h11 h12 h23 h24"/>
-      <!-- The representation of the weekday. -->
-      <option name="weekday" values="long short narrow"/>
-      <!-- The representation of the era. -->
-      <option name="era" values="long short narrow"/>
-      <!-- The representation of the year. -->
-      <option name="year" values="numeric 2-digit"/>
-      <!-- The representation of the month. -->
-      <option name="month" values="numeric 2-digit long short narrow"/>
-      <!-- The representation of the day. -->
-      <option name="day" values="numeric 2-digit"/>
-      <!-- The representation of the hour. -->
-      <option name="hour" values="numeric 2-digit"/>
-      <!-- The representation of the minute. -->
-      <option name="minute" values="numeric 2-digit"/>
-      <!-- The representation of the second. -->
-      <option name="second" values="numeric 2-digit"/>
-      <!-- The number of digits used to represent fractions of a second
-        (any additional digits are truncated). -->
-      <option name="fractionalSecondDigits" values="1 2 3"/>
-      <!-- The localized representation of the time zone name. -->
-      <option name="timeZoneName" values="long short shortOffset longOffset shortGeneric longGeneric"/>
+      <option name="calendar" values="buddhist chinese coptic dangi ethioaa ethiopic gregory hebrew indian islamic islamic-umalqura islamic-tbla islamic-civil islamic-rgsa iso8601 japanese persian roc">
+        <description>
+          Calendar to use.
+        </description>
+      </option>
+      <option name="dayPeriod" values="narrow short long">
+        <description>
+          The formatting style used for day periods like "in the morning", "am", "noon", "n" etc.
+        </description>
+      </option>
+      <option name="numberingSystem" values="arab arabext bali beng deva fullwide gujr guru hanidec khmr knda laoo latn limb mlym mong mymr orya tamldec telu thai tibt">
+        <description>
+          Numbering system to use.
+        </description>
+      </option>
+      <option name="timeZone" validationRule="timeZoneId">
+        <description>
+          The time zone to use.
+          The only value implementations must recognize is "UTC";
+          the default is the runtime's default time zone.
+          Implementations may also recognize the time zone names of the IANA time zone database,
+          such as "Asia/Shanghai", "Asia/Kolkata", "America/New_York".
+        </description>
+      </option>
+      <option name="hourCycle" values="h11 h12 h23 h24">
+        <description>
+          The hour cycle to use.
+        </description>
+      </option>
+      <option name="weekday" values="long short narrow">
+        <description>
+          The representation of the weekday.
+        </description>
+      </option>
+      <option name="era" values="long short narrow">
+        <description>
+          The representation of the era.
+        </description>
+      </option>
+      <option name="year" values="numeric 2-digit">
+        <description>
+          The representation of the year.
+        </description>
+      </option>
+      <option name="month" values="numeric 2-digit long short narrow">
+        <description>
+          The representation of the month.
+        </description>
+      </option>
+      <option name="day" values="numeric 2-digit">
+        <description>
+          The representation of the day.
+        </description>
+      </option>
+      <option name="hour" values="numeric 2-digit">
+        <description>
+          The representation of the hour.
+        </description>
+      </option>
+      <option name="minute" values="numeric 2-digit">
+        <description>
+          The representation of the minute.
+        </description>
+      </option>
+      <option name="second" values="numeric 2-digit">
+        <description>
+          The representation of the second.
+        </description>
+      </option>
+      <option name="fractionalSecondDigits" values="1 2 3">
+        <description>
+          The number of digits used to represent fractions of a second
+          (any additional digits are truncated).
+        </description>
+      </option>
+      <option name="timeZoneName" values="long short shortOffset longOffset shortGeneric longGeneric">
+        <description>
+          The localized representation of the time zone name.
+        </description>
+      </option>
     </formatSignature>
 
   </function>
 
   <function name="number">
     <!-- https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl/NumberFormat/NumberFormat -->
-    <description>Locale-sensitive number formatting</description>
+    <description>
+      Locale-sensitive number formatting
+    </description>
 
     <formatSignature>
       <input validationRule="anyNumber"/>
-      <!-- Only used when notation is "compact". -->
-      <option name="compactDisplay" values="short long" default="short"/>
-      <!-- The currency to use in currency formatting.
-        Possible values are the ISO 4217 currency codes, such as "USD" for the US dollar,
-        "EUR" for the euro, or "CNY" for the Chinese RMB — see the
-        Current currency & funds code list
-        (https://www.six-group.com/en/products-services/financial-information/data-standards.html#scrollTo=currency-codes).
-        There is no default value; if the style is "currency", the currency property must be provided.
-      -->
-      <option name="currency" validationRule="currencyCode"/>
-      <!-- How to display the currency in currency formatting. -->
-      <option name="currencyDisplay" values="symbol narrowSymbol code name" default="symbol"/>
-      <!-- In many locales, accounting format means to wrap the number with parentheses
-        instead of appending a minus sign. You can enable this formatting by setting the
-        currencySign option to "accounting".
-      -->
-      <option name="currencySign" values="accounting standard" default="standard"/>
-      <!-- The formatting that should be displayed for the number. -->
-      <option name="notation" values="standard scientific engineering compact" default="standard"/>
-      <!-- Numbering system to use. -->
-      <option name="numberingSystem" values="arab arabext bali beng deva fullwide gujr guru hanidec khmr knda laoo latn limb mlym mong mymr orya tamldec telu thai tibt"/>
-      <!-- When to display the sign for the number. -->
-      <!-- "negative" value is Experimental. -->
-      <option name="signDisplay" values="auto always exceptZero never" default="auto"/>
-      <!-- The formatting style to use. -->
-      <option name="style" values="decimal currency percent unit" default="decimal"/>
-      <!-- The unit to use in unit formatting.
-        Possible values are core unit identifiers, defined in UTS #35, Part 2, Section 6.
-        A subset of units from the full list was selected for use in ECMAScript.
-        Pairs of simple units can be concatenated with "-per-" to make a compound unit.
-        There is no default value; if the style is "unit", the unit property must be provided.
-      -->
-      <option name="unit" validationRule="anythingNotEmpty"/>
-      <!-- The unit formatting style to use in unit formatting. -->
-      <option name="unitDisplay" values="long short narrow" default="short"/>
-      <!-- The minimum number of integer digits to use.
-        A value with a smaller number of integer digits than this number will be
-        left-padded with zeros (to the specified length) when formatted.
-      -->
-      <option name="minimumIntegerDigits" values="positiveInteger" default="1"/>
-      <!-- The minimum number of fraction digits to use.
-        The default for plain number and percent formatting is 0;
-        the default for currency formatting is the number of minor unit digits provided by
-        the ISO 4217 currency code list (2 if the list doesn't provide that information).
-      -->
-      <option name="minimumFractionDigits" values="positiveInteger"/>
-      <!-- The maximum number of fraction digits to use.
-        The default for plain number formatting is the larger of minimumFractionDigits and 3;
-        the default for currency formatting is the larger of minimumFractionDigits and the number of minor
-        unit digits provided by the ISO 4217 currency code list (2 if the list doesn't provide that information);
-        the default for percent formatting is the larger of minimumFractionDigits and 0.
-      -->
-      <option name="maximumFractionDigits" values="positiveInteger"/>
-      <!-- The minimum number of significant digits to use. -->
-      <option name="minimumSignificantDigits" values="positiveInteger" default="1"/>
-      <!-- The maximum number of significant digits to use. -->
-      <option name="maximumSignificantDigits" values="positiveInteger" default="21"/>
+      <option name="compactDisplay" values="short long" default="short">
+        <description>
+          Only used when notation is "compact".
+        </description>
+      </option>
+      <option name="currency" validationRule="currencyCode">
+        <description>
+          The currency to use in currency formatting.
+          Possible values are the ISO 4217 currency codes, such as "USD" for the US dollar,
+          "EUR" for the euro, or "CNY" for the Chinese RMB — see the
+          Current currency &amp; funds code list
+          (https://www.unicode.org/cldr/charts/latest/supplemental/detailed_territory_currency_information.html).
+          There is no default value; if the style is "currency", the currency property must be provided.
+        </description>
+      </option>
+      <option name="currencyDisplay" values="symbol narrowSymbol code name" default="symbol">
+        <description>
+          How to display the currency in currency formatting.
+        </description>
+      </option>
+      <option name="currencySign" values="accounting standard" default="standard">
+        <description>
+          In many locales, accounting format means to wrap the number with parentheses
+          instead of appending a minus sign. You can enable this formatting by setting the
+          currencySign option to "accounting".
+        </description>
+      </option>
+      <option name="notation" values="standard scientific engineering compact" default="standard">
+        <description>
+          The formatting that should be displayed for the number.
+        </description>
+      </option>
+      <option name="numberingSystem" values="arab arabext bali beng deva fullwide gujr guru hanidec khmr knda laoo latn limb mlym mong mymr orya tamldec telu thai tibt">
+        <description>
+          Numbering system to use.
+        </description>
+      </option>
+      <option name="signDisplay" values="auto always exceptZero never" default="auto">
+        <description>
+          When to display the sign for the number. "negative" value is Experimental.
+        </description>
+      </option>
+      <option name="style" values="decimal currency percent unit" default="decimal">
+        <description>
+          The formatting style to use.
+        </description>
+      </option>
+      <option name="unit" validationRule="anythingNotEmpty">
+        <description>
+          The unit to use in unit formatting.
+          Possible values are core unit identifiers, defined in UTS #35, Part 2, Section 6.
+          A subset of units from the full list was selected for use in ECMAScript.
+          Pairs of simple units can be concatenated with "-per-" to make a compound unit.
+          There is no default value; if the style is "unit", the unit property must be provided.
+        </description>
+      </option>
+      <option name="unitDisplay" values="long short narrow" default="short">
+        <description>
+          The unit formatting style to use in unit formatting.
+        </description>
+      </option>
+      <option name="minimumIntegerDigits" values="positiveInteger" default="1">
+        <description>
+          The minimum number of integer digits to use.
+          A value with a smaller number of integer digits than this number will be
+          left-padded with zeros (to the specified length) when formatted.
+        </description>
+      </option>
+      <option name="minimumFractionDigits" values="positiveInteger">
+        <description>
+          The minimum number of fraction digits to use.
+          The default for plain number and percent formatting is 0;
+          the default for currency formatting is the number of minor unit digits provided by
+          the ISO 4217 currency code list (2 if the list doesn't provide that information).
+        </description>
+      </option>
+      <option name="maximumFractionDigits" values="positiveInteger">
+        <description>
+          The maximum number of fraction digits to use.
+          The default for plain number formatting is the larger of minimumFractionDigits and 3;
+          the default for currency formatting is the larger of minimumFractionDigits and the number of minor
+          unit digits provided by the ISO 4217 currency code list (2 if the list doesn't provide that information);
+          the default for percent formatting is the larger of minimumFractionDigits and 0.
+        </description>
+      </option>
+      <option name="minimumSignificantDigits" values="positiveInteger" default="1">
+        <description>
+          The minimum number of significant digits to use.
+        </description>
+      </option>
+      <option name="maximumSignificantDigits" values="positiveInteger" default="21">
+        <description>
+          The maximum number of significant digits to use.
+        </description>
+      </option>
     </formatSignature>
 
     <alias name="integer">