mandatory, obligatory, required, mandated, obligative, obligate, obligable, dutybound, duty bound, requirable, more...

optional, voluntary, elective, discretionary, nonmandatory

military, civil, religious, educational, parental, marital, judicial, more...

primary, elementary, military, such, religious, english, public, civil, hindi, physical, pilotage

not optional,   without a choice,   it's not optional,   subject) mandatory,   given by force,   mandate enforced,   forced expression,   making mandatory,   forced orders,   out of obligation