Was die type-Eigenschaft angeht, so ist definiert, dass sie lowercase sein muss.
http://www.w3.org/TR/DOM-Level-2-HTML/html.html#ID-62883744
Wird durch HTML5 ersetzt:
http://dev.w3.org/html5/spec/the-input-element.html
»The autocomplete and type IDL attributes must reflect the respective content attributes of the same name, limited to only known values.«
http://dev.w3.org/html5/spec/common-dom-interfaces.html#limited-to-only-known-values
»If a reflecting IDL attribute is a DOMString attribute whose content attribute is an enumerated attribute, and the IDL attribute is limited to only known values, then, on getting, the IDL attribute must return the conforming value associated with the state the attribute is in (in its canonical case) [...]«
Und die möglichen Typen sind hier definiert, allesamt lowercase:
http://dev.w3.org/html5/spec/the-input-element.html#attr-input-type-keywords
Mathias