Non-Capturing Group(?:\G(?!\A)|abc\s+d) \Gstart of current search
abcthe literal text abc (case sensitive) \s+any whitespace character, repeated at least once
dthe literal d (10010 / 1448 / 6416) (case sensitive)
\s*any whitespace character, 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
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