noun which may take the genitive case particle 'no'
the relevant; the said; the appropriate
Formal modifier used in legal, business, and official contexts to refer to a specific person, thing, or matter previously mentioned or under consideration. Often translates to 'the relevant', 'the said', or 'the appropriate' depending on context.
当該書類は、明日までにご提出ください。
Please submit the relevant documents by tomorrow.
当該人物の身元はまだ確認されていない。
The identity of the said person has not yet been confirmed.
当該地域の住民に避難勧告が出された。
An evacuation advisory was issued to residents of the affected area.
Compound of 当 (this, the present) and 該 (corresponding, applicable). The combination creates a formal term for 'the relevant/said'.