(?i)applies the following effective flags to the remainder of the pattern: gmi i modifier: insensitive. Matches without distinguishing uppercase and lowercase letters
^start of line
\S+any non-whitespace character, repeated at least once
\s+any whitespace character, repeated at least once
?repeats the group contents below at most once:
\d{2}a digit, repeated exactly 2 times
\d{2}a digit, repeated exactly 2 times
\s*any whitespace character, repeated any number of times
Non-Capturing Group(?:[-_]|to) -the literal - (4510 / 558 / 2D16)
_the literal _ (9510 / 1378 / 5F16)
tothe literal text to (case insensitive) \s*any whitespace character, repeated any number of times
presentthe literal text present (case insensitive) \S+any non-whitespace character, repeated at least once
\s*any whitespace character, repeated any number of times
?repeats the group contents below at most once:
\d{2}a digit, repeated exactly 2 times
?repeats the group contents below at most once:
\d{2}a digit, repeated exactly 2 times
$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