Timeline for "must" vs "shall" - are they the same, or is one a softened version of the other?

8 events

when toggle format	what		by	license	comment
May 23, 2021 at 1:32	comment	added	Jasen		ah, so you really meant "All students must enter the gym only through the side door this week." not creating a compulsion to enter the gym only a restriction on the method of doing so,
May 21, 2021 at 11:02	comment	added	MSalters		@alephzero: I don't think it's ambiguous. Your first interpretation would match "All students must enter the gym this week, through the side door." But that comma is not optional there. The presence of the comma disambiguates the two meanings.
May 21, 2021 at 3:39	comment	added	alephzero		"All students must enter the gym..." is ambiguous. Does it mean "Every student is required to enter the gym this week, and must enter using the side door" or "Students who enter the gym this week must use the side door, but entering the gym is not compulsory" ??
May 20, 2021 at 17:45	history	edited	Lambie	CC BY-SA 4.0	added 190 characters in body
May 20, 2021 at 17:15	history	edited	Lambie	CC BY-SA 4.0	added 38 characters in body
May 20, 2021 at 17:09	history	edited	Lambie	CC BY-SA 4.0	added 748 characters in body
May 20, 2021 at 16:54	history	edited	Lambie	CC BY-SA 4.0	added 748 characters in body
May 20, 2021 at 16:29	history	answered	Lambie	CC BY-SA 4.0