^start of line
urn:abc:de:xyz:the literal text urn:abc:de:xyz: (case sensitive) \d{6,12}a digit, repeated between 6 and 12 times
\.the literal . (4610 / 568 / 2E16)
\d{1,7}a digit, repeated between 1 and 7 times
Non-Capturing Group(?:\.[\w-]{1,20})+ +repeats the group contents below at least once:
\.the literal . (4610 / 568 / 2E16)
Character Class[\w-]{1,20} {1,20}matches between 1 and 20 characters from the set below:
\wany word character
-the literal - (4510 / 558 / 2D16)
$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