att.declaring provides attributes for elements which may be independently associated with a particular declarable element within the header, thus overriding the inherited default for that element. [15.3. Associating Contextual Information with a Text]
Membersab back body div facsimile floatingText front geo gloss graphic group lg listAnnotation media msDesc object p ptr ref sourceDoc standOff surface surfaceGrp term text
decls(declarations) identifies one or more declarable elements within the header, which are understood to apply to the element bearing this attribute and its content.
Status Optional
Datatype 1–∞ occurrences of teidata.pointer separated by whitespace

The rules governing the association of declarable elements with individual parts of a TEI text are fully defined in chapter 15.3. Associating Contextual Information with a Text.