^start of line
\s{2}a Unicode whitespace character, repeated exactly 2 times
+matches at least one character from the set below:
0-9one character from 0 (4810) to 9 (5710)
\sa Unicode whitespace character
=the literal = (6110 / 758 / 3D16)
\sa Unicode whitespace character
"the literal " (3410 / 428 / 2216)
Negative Lookahead(?!(?:Section|Page|Heading)\b) Non-Capturing Group(?:Section|Page|Heading) Sectionthe literal text Section (case sensitive) Pagethe literal text Page (case sensitive) Headingthe literal text Heading (case sensitive) \ba Unicode word boundary
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