OXIO Source: official citation (supplied in headnote)
Capture the official citation within the source XML itself, using the value supplied in the headnote ("Official citation"). If there are multiple official citations listed (separated by a semicolon), separate them with | pipes.
Instruments (OxLawML):
/regGroup/regMeta/citeGrp/bibItem/@idnumber
Cases (OxLawRepML):
/case/headNote/citeGrp/bibItem/@idnumber
Commentaries (OxStructML):
/document/regMeta/citeGrp/bibItem/@idnumber