+repeats the group contents below at least once:
\d{1,4}a Unicode decimal digit, repeated between 1 and 4 times
?matches at most one character from the set below:
.the literal . (4610 / 568 / 2E16)
-the literal - (4510 / 558 / 2D16)
?matches at most one character from the set below:
a-zone character from a (9710) to z (12210) (case sensitive)
A-Zone character from A (6510) to Z (9010) (case sensitive)
\s*a Unicode whitespace character, repeated any number of times
,?optionally matches the literal , (4410 / 548 / 2C16)
\s*a Unicode whitespace character, repeated any number of times