Please see Strings · The Julia Language Regular Expression.
s Treat string as single line. That is, change “.” to match any
character whatsoever, even a newline , which normally it would
not match.
i Do case-insensitive pattern matching.
If locale matching rules are in effect, the case map is taken
from the current locale for code points less than 255, and
from Unicode rules for larger code points. However, matches
that would cross the Unicode rules/non-Unicode rules boundary
(ords 255/256) will not succeed.
m Treat string as multiple lines. That is, change "^" and "$"
from matching the start or end of the string to matching the
start or end of any line anywhere within the string.
s Treat string as single line. That is, change "." to match any
character whatsoever, even a newline, which normally it would
not match.
Used together, as r""ms, they let the "." match any character
whatsoever, while still allowing "^" and "$" to match,
respectively, just after and just before newlines within the
string.
x Tells the regular expression parser to ignore most whitespace
that is neither backslashed nor within a character class. You
can use this to break up your regular expression into
(slightly) more readable parts. The '#' character is also
treated as a metacharacter introducing a comment, just as in
ordinary code.