/usr/share/xml/dia/diagram.dtd is in dia-common 0.97.2-5.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 | <!ELEMENT dia:diagram (dia:diagramdata, (dia:layer)*) >
<!ATTLIST dia:diagram
xmlns:dia CDATA #FIXED "http://www.lysator.liu.se/~alla/dia/">
<!ELEMENT dia:diagramdata (dia:attribute)* >
<!ELEMENT dia:layer (dia:object | dia:group)*>
<!ATTLIST dia:layer
name CDATA #REQUIRED
visible (true|false) #REQUIRED
active (true|false) #IMPLIED>
<!ELEMENT dia:object ((dia:attribute)*, dia:connections?)>
<!ATTLIST dia:object
type CDATA #REQUIRED
version NMTOKEN #REQUIRED
id ID #REQUIRED >
<!ELEMENT dia:connections (dia:connection)*>
<!ELEMENT dia:connection EMPTY>
<!ATTLIST dia:connection
handle NMTOKEN #REQUIRED
to IDREF #REQUIRED
connection NMTOKEN #REQUIRED>
<!ELEMENT dia:group (dia:object | dia:group)*>
<!ELEMENT dia:attribute (dia:composite | dia:int | dia:enum | dia:real |
dia:boolean | dia:color | dia:point | dia:rectangle |
dia:string | dia:font)*>
<!ATTLIST dia:attribute name CDATA #REQUIRED >
<!ELEMENT dia:composite (dia:attribute|dia:composite)*>
<!ATTLIST dia:composite type CDATA #IMPLIED>
<!ELEMENT dia:int EMPTY>
<!ATTLIST dia:int val NMTOKEN #REQUIRED>
<!ELEMENT dia:enum EMPTY>
<!ATTLIST dia:enum val NMTOKEN #REQUIRED>
<!ELEMENT dia:real EMPTY>
<!ATTLIST dia:real val CDATA #REQUIRED>
<!ELEMENT dia:boolean EMPTY>
<!ATTLIST dia:boolean val (true|false) #REQUIRED>
<!ELEMENT dia:color EMPTY>
<!ATTLIST dia:color val CDATA #REQUIRED>
<!ELEMENT dia:point EMPTY>
<!ATTLIST dia:point val CDATA #REQUIRED>
<!ELEMENT dia:rectangle EMPTY>
<!ATTLIST dia:rectangle val CDATA #REQUIRED>
<!ELEMENT dia:string (#PCDATA)>
<!ELEMENT dia:font EMPTY>
<!ATTLIST dia:font
name CDATA #REQUIRED
style CDATA #IMPLIED
family CDATA #IMPLIED>
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