^start of line
Non-Capturing Group(?:\d,)? ?repeats the group contents below at most once:
\da Unicode decimal digit
,the literal , (4410 / 548 / 2C16)
\d{3}a Unicode decimal digit, repeated exactly 3 times
,the literal , (4410 / 548 / 2C16)
\d{3}a Unicode decimal digit, repeated exactly 3 times
$end of line
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