^start of line
\s*a Unicode whitespace character, repeated any number of times
pthe literal p (11210 / 1608 / 7016) (case sensitive)
L{1,3}the literal L (7610 / 1148 / 4C16) (case sensitive), repeated between 1 and 3 times
\s*a Unicode whitespace character, repeated any number of 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
u modifier: unicode. Treats the pattern and subject as UTF-16