^start of string
\d{2}a digit, repeated exactly 2 times
{1}matches one character from the set below:
1-3one character from 1 (4910) to 3 (5110)
Negative Lookahead(?!0{4}|9{4}) 0{4}the literal 0 (4810 / 608 / 3016) , repeated exactly 4 times
9{4}the literal 9 (5710 / 718 / 3916) , repeated exactly 4 times
\d{4}a digit, repeated exactly 4 times
{1}matches one character from the set below:
0-6one character from 0 (4810) to 6 (5410)
\d{2}a digit, repeated exactly 2 times
$end of string, or before its final line terminator
g modifier: global. Finds all matches instead of stopping after the first