<locus>defines a location within a manuscript or manuscript part, usually as a (possibly discontinuous) sequence of folio references.
Attributes:
schemeidentifies the foliation scheme in terms of which the location is being specified
Datatype: CDATA
Values: Identifies a foliation scheme, as further defined in the <foliation> element
Default: #IMPLIED
fromspecifies the starting point of the location in a normalised form
Datatype: CDATA
Values: typically this will be a page number
Default: #IMPLIED
tospecifies the end-point of the location in a normalized form
Datatype: CDATA
Values: typically this will be a page number
Default: #IMPLIED
targetssupplies identifiers of associated page images
Datatype: IDREFS
Values: a list of SGML identifiers, either of <figure> elements within a transcript containing digitized page images, or of <xptr> elements linked to such images
Default: #IMPLIED
Example
<locus targets="P12 P13 P14 P16">fols 12-14, 16r</locus>
Class
Declaration
<!ELEMENT locus  - -  (#PCDATA)>
<!ATTLIST	locus	%a.global;
	                scheme  CDATA           #IMPLIED
			from	CDATA		#IMPLIED
			to	CDATA		#IMPLIED
			targets	IDREFS		#IMPLIED>
See further2.2.3. References to manuscript locations

Appendix A Reference Documentation for Elements and Classes