(?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
.*?any character (except for line terminators), repeated any number of times
\Kresets the starting point of the reported match. Any previously consumed characters are no longer included in the final match
Negative Lookbehind(?<!\S) \Sany non-whitespace character
*matches any number of characters from the set below:
b-zone character from b (9810) to z (12210) (case insensitive)
athe literal a (9710 / 1418 / 6116) (case insensitive)
*matches any number of characters from the set below:
a-zone character from a (9710) to z (12210) (case insensitive)
\Sany non-whitespace character
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