Mandatary n. : One to whom a command or charge is given; hence, specifically, a person to whom the pope has, by his prerogative, given a mandate or order for his benefice.

Mandatary n. : One who undertakes to discharge a specific business commission; a mandatory.

Example:
what is the minimum population of a city where sewerage system is Mandatary as per WHO norms or Indian laws?

Taxonomy
mandatory, Encyclopedia, Law, Dictionary, mandat, authority, American Law, Mandatory Authority, Antonyms, provision, Houghton Mifflin Company, insurance term, Attendance, the meeting, Thesaurus, Translations, Mandatory Subject, Mandatory Convertible.

Defination from the web:
mandatory adj. Required or commanded by authority; obligatory: Attendance at the meeting is mandatory ... A mandatory provision is one that must be observed, whereas a directory provision is optional. ...