Actually the norm is to use '1' only because this will not produce warnings if you do

perl somepackage.pm
[download]

But you can use any true value you like, the warnings will not be generated when the line is encountered in the context of a use or require. For instance I sometimes put "by demerphq"; as the last statement in the file.

--- demerphq
my friends call me, usually because I'm late....