^start of line
\*{2}the literal * (4210 / 528 / 2A16) , repeated exactly 2 times
Header2the literal text Header2 (case sensitive) \*{2}the literal * (4210 / 528 / 2A16) , repeated exactly 2 times
*the literal (3210 / 408 / 2016) , repeated any number of times
\na line-feed (newline) character (ASCII 10)
Group 1((?:(?!^\*{2}[^*]*\*{2}).)*?) Non-Capturing Group(?:(?!^\*{2}[^*]*\*{2}).)*? *?repeats the group contents below any number of times:
Negative Lookahead(?!^\*{2}[^*]*\*{2}) ^start of line
\*{2}the literal * (4210 / 528 / 2A16) , repeated exactly 2 times
Negated Character Class[^*]* *matches any number of characters outside the set below:
*the literal * (4210 / 528 / 2A16)
\*{2}the literal * (4210 / 528 / 2A16) , repeated exactly 2 times
.any Unicode character
Positive Lookahead(?=\s*^\*{2}[^*]*\*{2}|\s*\Z) 1st Alternative\s*^\*{2}[^*]*\*{2} \s*a Unicode whitespace character, repeated any number of times
^start of line
\*{2}the literal * (4210 / 528 / 2A16) , repeated exactly 2 times
Negated Character Class[^*]* *matches any number of characters outside the set below:
*the literal * (4210 / 528 / 2A16)
\*{2}the literal * (4210 / 528 / 2A16) , repeated exactly 2 times
\s*a Unicode whitespace character, repeated any number of times
\Zend of string
m modifier: multiline. Causes ^ and $ to match the start and end of each line, not only the start and end of the string
s modifier: single line. Allows a dot to match line terminators