^start of line
Non-Capturing Group(?:(?!xyz|1).)* *repeats the group contents below any number of times:
Negative Lookahead(?!xyz|1) xyzthe literal text xyz (case sensitive) 1the literal 1 (4910 / 618 / 3116)
.any character (except for line terminators)
1the literal 1 (4910 / 618 / 3116)
.*any character (except for line terminators), repeated any number of times
xyzthe literal text xyz (case sensitive) .*any character (except for line terminators), repeated any number of times
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