^start of line
Comment: Start of string
\#?optionally matches the literal # (3510 / 438 / 2316)
Comment: Optional "#"
{4}matches exactly 4 characters from the set below:
a-zone character from a (9710) to z (12210) (case sensitive)
Comment: Followed by 4 letters
\ ?optionally matches the literal (3210 / 408 / 2016)
Comment: Optional space
Comment: Followed by an underscore
?matches at most one character from the set below:
the literal (3210 / 408 / 2016)
Comment: Optional space
{6}matches exactly 6 characters from the set below:
0-9one character from 0 (4810) to 9 (5710)
Comment: Followed by 6 digits
?matches at most one character from the set below:
#the literal # (3510 / 438 / 2316)
Comment: Optional "#"
$end of line
Comment: End of string
g modifier: global. Finds all matches instead of stopping after the first
x modifier: extended. Ignores unescaped whitespace and comments outside character classes
m modifier: multiline. Causes ^ and $ to match the start and end of each line, not only the start and end of the string