validating wth missing DOCTYPE

Why is it impossible to validate a document without a DOCTYPE. Ok, I
know this documents does not validate, and there should be some warning
about it, but for what are then tne fields for selecting charset and
doctype? 
I mean I have a page. This page doesn't have a DOCTYPE. Ok, I know it's
not valid. But I want to force validating with one specific DOCTYPE to
sre how many other errors it contains. And I cannot. And as this is not
my page, I just want to come out with several improvement ideas, I
cannot just add the doctype and revalidate. And even if I could it would
be easier to force validating and then fix all errors at once.
PS I'm not subscribed, as I don't see any field for discussion about
this. But if I'm wrong I will subscribe
Torinthiel

-- 
 Waclaw "Torinthiel" Schiller       GG#: 542916, 3073512
   torinthiel(at)wp(dot)pl
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