\s+any whitespace character, repeated at least once
Negated Character Class[^:]+ +matches at least one character outside the set below:
:the literal : (5810 / 728 / 3A16)
:the literal : (5810 / 728 / 3A16)
\s+any whitespace character, repeated at least once
.+any character (except for line terminators), repeated at least once
g modifier: global. Finds all matches instead of stopping after the first
m modifier: multiline. Causes ^ and $ to match the start and end of each line, not only the start and end of the string