Mandatory sign: mandatory sign requires specific behaviors or action.

强制性标识：强制性标识是对行为或行动的明确要求。

youdao

But, let's be clear, a mandatory recall is a sign of failure.

但是，我们也清醒地认识到，强制召回是一个失灵的象征。

youdao

Why is it mandatory that I find a plus sign?

为何正号是强制的？

youdao

But he refuses to sign onto mandatory emission-reduction obligations, preferring to encourage the development of new technologies and other voluntary measures, and won't participate in any talks toward a global agreement that do not include energy guzzlers from the developing world.

NPR: Bush Calls for Goal on Reducing Greenhouse Gases

They'll sign in at village checkpoints, sometimes stopping for mandatory layovers.

NPR: Iditarod Kicks Off With Festive Ceremonial Start