The source attribute points to an external source. When used on elements describing schema components it locates the source for the ODD processor from which declarations and definitions for the components of the object being defined may be obtained. On other elements it provides a pointer to the bibliographical source from which a quotation or citation is drawn. These are provided as any form of URI, for example an absolute URI, a relative URI, or private scheme URI that is expanded to an absolute URI as documented in a prefixDef.
Example
<p> <!-- ... --> As Willard McCarty (<bibl xml:id="mcc_2012">2012, p.2</bibl>) tells us, <quote source="#mcc_2012">‘Collaboration’ is a problematic and should be a contested term.</quote> <!-- ... --> </p>
<p> <!-- ... --> <quote source="#chicago_15_ed">Grammatical theories are in flux, and the more we learn, the less we seem to know.</quote> <!-- ... --> </p> <!-- ... --> <bibl xml:id="chicago_15_ed"> <title level="m">The Chicago Manual of Style</title>, <edition>15th edition</edition>. <pubPlace>Chicago</pubPlace>: <publisher>University of Chicago Press</publisher> (<date>2003</date>), <biblScope unit="page">p.147</biblScope>.
</bibl>
Example
<elementRef key="p" source="tei:2.0.1"/>
Include in the schema an element named p available from the TEI P5 2.0.1 release.