Since when does Perl just ignore things? (: It gets parsed as "5.6" . "0"

Since I tried it and that's what happens? ato[id] will read as many chars as makes sence and ignores the rest. E.g.

sub I_want_a_number ($) { 
   my $val= shift;
   print $val, " produces ", 0+$val, "\n";
   }

I_want_a_number ("29 balloons");
I_want_a_number ("5.6.0");
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So, you say that using floats with 3-digit convention in the require statement (did it support use also, or just require, when first introduced?) e.g.require 5.006_001; will have the advantage of giving a reasonable message as far back as 5.005, but still give an unrelated message (file not found) for older. I wonder if the error message can be improved by a "spot change" in UNIVERSAL.pm, for those who can't/won't upgrade? When did the ability to have a sub on the @INC list show up? That can recognise the number for a module name and do the check itself!