Okay, Page 20, "Computer Science & Perl Programming", edited by Jon Orwant, Chapter 3, article title is Perfect Programming.
I'm not making this up:
Quote: When it's in effect, you can't use the bareword style of calling subroutines with no arguments (e.g. $result = mysub;) unless the subroutine was declared before its use, either with a prototype or with the subroutine definition itself.
use strict 'subs';
print count; # an error with use strict 'subs'
sub count; # prototyping count() is sufficient
print count; # Not an error because Perl now knows about count()
J. J. Horner