\d{2}a digit, repeated exactly 2 times
Group 1(0[1-9]|1[0-2]|5[1-9]|6[0-2]) 0the literal 0 (4810 / 608 / 3016)
1-9one character from 1 (4910) to 9 (5710)
1the literal 1 (4910 / 618 / 3116)
0-2one character from 0 (4810) to 2 (5010)
5the literal 5 (5310 / 658 / 3516)
1-9one character from 1 (4910) to 9 (5710)
6the literal 6 (5410 / 668 / 3616)
0-2one character from 0 (4810) to 2 (5010)
Group 2(0[1-9]|1[0-9]|2[0-9]|3[0-1]) 0the literal 0 (4810 / 608 / 3016)
1-9one character from 1 (4910) to 9 (5710)
1the literal 1 (4910 / 618 / 3116)
0-9one character from 0 (4810) to 9 (5710)
2the literal 2 (5010 / 628 / 3216)
0-9one character from 0 (4810) to 9 (5710)
3the literal 3 (5110 / 638 / 3316)
0-1one character from 0 (4810) to 1 (4910)
\/?optionally matches the literal / (4710 / 578 / 2F16)
\d{3,4}a digit, repeated between 3 and 4 times
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
i modifier: insensitive. Matches without distinguishing uppercase and lowercase letters