أنشئ حسابًا أو سجّل الدخول للانضمام إلى مجتمعك المهني.
The term "must" means "Bound To Do" or "Mandatory" obligations. And the term "shall' means "Should Be Done" or "Will Do" .
My view is that "must" implies a condition precedent whereas "shall" involves a strong element of compunction. A failure to observe a "must" is capable of correction but a failure to observe a "shall" requirement means that an action has failed and is probably incapable of being corrected.
The term "shall" and "shall not" is stronger than "must/should" and "must not/should not".