^start of line
Positive Lookahead(?=.{0,20}(.*)) .{0,20}any character (except for line terminators), repeated between 0 and 20 times
.*any character (except for line terminators), repeated any number of times
.*?any character (except for line terminators), repeated any number of times
\Kresets the starting point of the reported match. Any previously consumed characters are no longer included in the final match
\S+any non-whitespace character, repeated at least once
Vthe literal V (8610 / 1268 / 5616) (case sensitive)
\ban ASCII word boundary
Positive Lookahead(?=.*?\1) .*?any character (except for line terminators), repeated any number of times
\1the text saved by group 1
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