/usr/share/notebook/dtd/notebook.dtd is in notebook-gtk2 0.2rel-2.2.
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 | <!ELEMENT notelist (note)*>
<!ELEMENT note (title, content, date, lastupdate?, attachment)>
<!ATTLIST note
index CDATA #REQUIRED
type (note|personal|problem|trick|bookmark)
status (none|open|solved)
>
<!ELEMENT title (#PCDATA)>
<!ELEMENT content (#PCDATA)>
<!ELEMENT content (#PCDATA)>
<!ELEMENT date (day, month, year)>
<!ELEMENT lastupdate (day, month, year)>
<!ELEMENT day (#PCDATA)>
<!ELEMENT month (#PCDATA)>
<!ELEMENT year (#PCDATA)>
<!ELEMENT attachment (uri, mime, location)>
<!ELEMENT uri (#PCDATA)>
<!ELEMENT mime (#PCDATA)>
<!ELEMENT location (linked|moved)
|