^start of line
\d{3}a digit, repeated exactly 3 times
_the literal _ (9510 / 1378 / 5F16)
\d{1,2}a digit, repeated between 1 and 2 times
\.the literal . (4610 / 568 / 2E16)
Negated Character Class[^\W_]{1,3} {1,3}matches between 1 and 3 characters outside the set below:
\Wany non-word character
_the literal _ (9510 / 1378 / 5F16)
_the literal _ (9510 / 1378 / 5F16)
A-Zone character from A (6510) to Z (9010) (case sensitive)
{6}matches exactly 6 characters from the set below:
0-9one character from 0 (4810) to 9 (5710)
$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