What does * before a Perl variable name mean?

Question

What does the Perl statement below mean?

*INPUT_DATA                    =\ 0;

I checked some Perl documentation sites also like https://perldoc.perl.org/variables, but I couldn't find a similar example.

Answer 1

In short, * denotes a "typeglob", which is an internal type holding the values of all global variables of the given name. It's still sometimes used for filehandles in older code or to create aliases.

See perldata for the explanation of typeglobs, and also see the links recommended at the end of the page, i.e. perlvar, perlref, perlsub, and perlmod.