diff --git a/java/res/values/attrs.xml b/java/res/values/attrs.xml
index d574b9e..573ec68 100644
--- a/java/res/values/attrs.xml
+++ b/java/res/values/attrs.xml
@@ -300,6 +300,7 @@
             <flag name="disableAdditionalMoreKeys" value="0x80000000" />
         </attr>
         <!-- The icon to display on the key instead of the label. -->
+        <!-- TODO: Use string format !icon/name. -->
         <attr name="keyIcon" format="enum">
             <!-- This should be aligned with the KeyboardIconsSet.ICON_* -->
             <enum name="iconUndefined" value="0" />
@@ -319,11 +320,13 @@
             <enum name="iconZwjKey" value="16" />
         </attr>
         <!-- The icon for disabled key -->
+        <!-- TODO: Use string format !icon/name. -->
         <attr name="keyIconDisabled" format="enum">
             <!-- This should be aligned with the KeyboardIconsSet.ICON_* -->
             <enum name="iconDisabledShortcutKey" value="12" />
         </attr>
         <!-- The icon to show in the popup preview. -->
+        <!-- TODO: Use string format !icon/name. -->
         <attr name="keyIconPreview" format="enum">
             <!-- This should be aligned with the KeyboardIconsSet.ICON_* -->
             <enum name="iconPreviewTabKey" value="13" />
diff --git a/java/res/values/donottranslate-more-keys.xml b/java/res/values/donottranslate-more-keys.xml
index 5e97edc..14c278a 100644
--- a/java/res/values/donottranslate-more-keys.xml
+++ b/java/res/values/donottranslate-more-keys.xml
@@ -120,7 +120,7 @@
          U+2205: "∅" EMPTY SET -->
     <string name="more_keys_for_symbols_0">&#x207F;,&#x2205;</string>
     <string name="more_keys_for_am_pm">!fixedColumnOrder!2,!hasLabels!,\@string/label_time_am,\@string/label_time_pm</string>
-    <string name="settings_as_more_key">\@icon/settingsKey|!code/key_settings</string>
+    <string name="settings_as_more_key">!icon/settingsKey|!code/key_settings</string>
     <string name="keylabel_for_comma">,</string>
     <string name="more_keys_for_comma"></string>
     <string name="action_next_as_more_key">!hasLabels!,\@string/label_next_key|!code/key_action_next</string>
diff --git a/java/res/xml-sw600dp/key_styles_common.xml b/java/res/xml-sw600dp/key_styles_common.xml
index 3cec9aa..b0f6109 100644
--- a/java/res/xml-sw600dp/key_styles_common.xml
+++ b/java/res/xml-sw600dp/key_styles_common.xml
@@ -84,7 +84,7 @@
         latin:styleName="zwnjKeyStyle"
         latin:code="0x200C"
         latin:keyIcon="iconZwnjKey"
-        latin:moreKeys="\@icon/zwjKey|&#x200D;"
+        latin:moreKeys="!icon/zwjKey|&#x200D;"
         latin:keyLabelFlags="hasPopupHint"
         latin:keyActionFlags="noKeyPreview" />
     <key-style
diff --git a/java/res/xml-sw768dp/key_styles_common.xml b/java/res/xml-sw768dp/key_styles_common.xml
index c3ad195..aa9cd69 100644
--- a/java/res/xml-sw768dp/key_styles_common.xml
+++ b/java/res/xml-sw768dp/key_styles_common.xml
@@ -83,7 +83,7 @@
         latin:styleName="zwnjKeyStyle"
         latin:code="0x200C"
         latin:keyIcon="iconZwnjKey"
-        latin:moreKeys="\@icon/zwjKey|&#x200D;"
+        latin:moreKeys="!icon/zwjKey|&#x200D;"
         latin:keyLabelFlags="hasPopupHint"
         latin:keyActionFlags="noKeyPreview" />
     <key-style
diff --git a/java/res/xml/key_styles_common.xml b/java/res/xml/key_styles_common.xml
index bd002fd..b0b87a8 100644
--- a/java/res/xml/key_styles_common.xml
+++ b/java/res/xml/key_styles_common.xml
@@ -113,7 +113,7 @@
         latin:styleName="zwnjKeyStyle"
         latin:code="0x200C"
         latin:keyIcon="iconZwnjKey"
-        latin:moreKeys="\@icon/zwjKey|&#x200D;"
+        latin:moreKeys="!icon/zwjKey|&#x200D;"
         latin:keyLabelFlags="hasPopupHint"
         latin:keyActionFlags="noKeyPreview"
         latin:backgroundType="functional" />
diff --git a/java/src/com/android/inputmethod/keyboard/internal/KeySpecParser.java b/java/src/com/android/inputmethod/keyboard/internal/KeySpecParser.java
index 84965bf..288fb45 100644
--- a/java/src/com/android/inputmethod/keyboard/internal/KeySpecParser.java
+++ b/java/src/com/android/inputmethod/keyboard/internal/KeySpecParser.java
@@ -32,10 +32,11 @@
  * - String resource can be embedded into specification @string/name. This is done before parsing
  *   comma.
  * Each "more key" specification is one of the following:
- * - A single letter (Letter)
  * - Label optionally followed by keyOutputText or code (keyLabel|keyOutputText).
- * - Icon followed by keyOutputText or a string representation of codes
- *   (@icon/icon_name|!code/key_code)
+ * - Icon followed by keyOutputText or code (!icon/icon_name|!code/code_name)
+ *   - Icon should be a string representation of icon (!icon/icon_name).
+ *   - Code should be a code point presented by hexadecimal string prefixed with "0x".
+ *     Or a string representation of code (!code/code_name).
  * Special character, comma ',' backslash '\', and bar '|' can be escaped by '\' character.
  * Note that the character '@' and '\' are also parsed by XML parser and CSV parser as well.
  * See {@link KeyboardIconsSet} about icon_name.
@@ -52,7 +53,7 @@
     private static final char SUFFIX_SLASH = '/';
     private static final String PREFIX_STRING = PREFIX_AT + "string" + SUFFIX_SLASH;
     private static final char LABEL_END = '|';
-    private static final String PREFIX_ICON = PREFIX_AT + "icon" + SUFFIX_SLASH;
+    private static final String PREFIX_ICON = "!icon/";
     private static final String PREFIX_CODE = "!code/";
     private static final String PREFIX_HEX = "0x";
     private static final String ADDITIONAL_MORE_KEY_MARKER = "%";