<!ELEMENT Component (Subcomponent+)>
<!ATTLIST Component
 Abbr ID #REQUIRED
 Name CDATA #REQUIRED
>
<!ELEMENT LevelOne (#PCDATA)>
<!ELEMENT LevelTwo (#PCDATA)>
<!ELEMENT Message (LevelOne, LevelTwo)>
<!ATTLIST Message
 ID CDATA #REQUIRED
 Indicator (I | E | W | U | Q | C) #REQUIRED
>
<!ELEMENT MessageFile (Component)>
<!ATTLIST MessageFile
 Version CDATA #FIXED "1.0"
>
<!ELEMENT MessageList (Message+)>
<!ELEMENT Subcomponent (MessageList)>
<!ATTLIST Subcomponent
 Abbr ID #REQUIRED
 Name CDATA #REQUIRED
>