I must say that this is a term that I forgot that I knew. In Supply Chain we get to know the term intermodal. Yet this is different. There are a number of modals that are common in the English language and I will try and explain just two. See the infographics below for the others.
When creating a request for bid document you have to be very careful in the proper use of must/may. The over use of must and its siblings shall and will can cause you to reject a larger number of proposals/submissions.
What I am outlining is not legal advice. It is common sense that too much of a good things isn’t always what you need. Too many musts or mays can cause even the most seasoned professionals some challenges.