\[the literal [ (9110 / 1338 / 5B16)
plantumlthe literal text plantuml (case sensitive) .+any character (except for line terminators), repeated at least once
\]the literal ] (9310 / 1358 / 5D16)
\s+any whitespace character, repeated at least once
\.{4}the literal . (4610 / 568 / 2E16) , repeated exactly 4 times
\sany whitespace character
Group 2([\s\S]+?(?=^\.{4})) +?matches at least one character from the set below:
\sany whitespace character
\Sany non-whitespace character
Positive Lookahead(?=^\.{4}) ^start of line
\.{4}the literal . (4610 / 568 / 2E16) , repeated exactly 4 times
\.{4}the literal . (4610 / 568 / 2E16) , repeated exactly 4 times
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