\d+a Unicode decimal digit, repeated at least once
\.the literal . (4610 / 568 / 2E16)
.+?any Unicode character (except for line terminators), repeated at least once
\s+a Unicode whitespace character, repeated at least once
\da Unicode decimal digit
.+?any Unicode character (except for line terminators), repeated at least once
\d+a Unicode decimal digit, repeated at least once
Positive Lookahead(?=$|\s+(?:\[|[A-Z])) 2nd Alternative\s+(?:\[|[A-Z]) \s+a Unicode whitespace character, repeated at least once
Non-Capturing Group(?:\[|[A-Z]) \[the literal [ (9110 / 1338 / 5B16)
A-Zone character from A (6510) to Z (9010) (case sensitive)
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