In the case of the BNC the header information supplies data about the length of the text, who wrote it and where it was found, who processed it for the BNC and when, copyright issues, etc.
The whole text file starts with <bncDOC and some form of identification:
in the case of text file A0T, and ends with
in the XML edition you will find xml in the header and to conform to XML specifications, double quote characters are used around each attribute:
The header section starts with something like this:
<teiHeader type="text" status="update" date.updated="2000-12-13">
and ends with
<text decls='CN001 HN001 QN000 SN000'><body>