ODD

ODD is "One Document Does it all".

The TEI Guidelines, its DTD, and its schema fragments, are all produced from a single XML resource containing:

1. Descriptive prose (lots of it)
2. Examples of usage (plenty)
3. Formal declarations for components of the TEI Abstract Model:
   1. elements and attributes
   2. modules
   3. classes and macros
4. We call this resource an ODD (One Document Does it all) although the master source is instantiated as a gazillion XML mini-documents.

The TEI scheme can only be used by customizing it. Customizations are also expressed in the ODD language. For example:

<schemaSpec ident="myTEIlite">
<desc>This is TEI Lite with simplified heads</desc>
  <moduleRef name="teistructure"/>
  <moduleRef name="linking"/>
  <moduleRef name="core"/>
  <moduleRef name="teiheader"/>
  <elementSpec ident="head" mode="change">
    <content><rng:text/></content>
  </elementSpec>
</schemaSpec>

produces the schema for TEI Lite, with a slight change