Difference between regular expression modifiers (or flags) 'm' and 's'?

Question

I often forget about the regular expression modifiers m and s and their differences. What is a good way to remember them?

As I understand t

Answer 1

I like the explanation in 'man perlre':

m Treat string as multiple lines.
s Treat string as single line.

With multiple lines, ^ and $ apply to individual lines (i.e. just before and after newlines).
With a single line, ^ and $ apply to the whole, and \n just becomes another character you can match.

[Wrong]By using both m and s as you described, I would expect the second one to take precedence, so you would always be in multiline mode with /ism.[/Wrong]

I didn't read far enough:
The "/s" and "/m" modifiers both override the $* setting. That is, no matter what $* contains, "/s" without "/m" will force "^" to match only at the beginning of the string and "$" to match only at the end (or just before a newline at the end) of the string. Together, as /ms, they let the "." match any character whatsoever, while still allowing "^" and "$" to match, respectively, just after and just before newlines within the string.