[XML-SIG] Missing DOCTYPE when pretty printing

[Martin v. Loewis]

> Likely to be deliberate, because I don't think you can have a DOCTYPE
> without a system ID

Why is that? If the doctype only consists of an internal subset, then
there is nothing wrong with not having a system id, e.g. as in

<!DOCTYPE foo [
 <!ELEMENT foo (bar*)>
 <!ELEMENT bar (#PCDATA)>
]>


> <!DOCTYPE PUBLIC pubId systemId>
> <!DOCTYPE SYSTEM systemId>

I think the name of the root element is required. The syntax of
doctypedecl is

[28] doctypedecl ::= '<!DOCTYPE' S Name (S ExternalID)? S? 
            ('[' (markupdecl | PEReference | S)* ']' S?)? '>'

where ExternalId is

[75] ExternalID ::= 'SYSTEM' S SystemLiteral | 
                    'PUBLIC' S PubidLiteral S SystemLiteral

So you can't have a public ID without a system ID; you certainly can
have neither.

A related question: Is it well-formed to have neither system id nor
internal subset, i.e.

<!DOCTYPE foo>

If well-formed, can that ever appear in a valid document?

Regards,
Martin