?repeats the group contents below at most once:
\d{4}a Unicode decimal digit, repeated exactly 4 times
-the literal - (4510 / 558 / 2D16)
\d{2}a Unicode decimal digit, repeated exactly 2 times
-the literal - (4510 / 558 / 2D16)
\d{2}a Unicode decimal digit, repeated exactly 2 times