Question on attribute values

Keith Ball (kball@kballuw.SJF.Novell.COM)
Tue, 25 Oct 94 21:16:50 EDT

I need to verify my understanding of the attribute value requirements
covered in section 3.4.3 of the Oct 13 version of the spec.

Here are some statements that I believe are true. If they are not,
please tell so.

1) attribute values that are defined as CDATA, such as ALT for
the IMG element, MUST be quote delimited even if they do NOT contain
spaces (0x20) or ">".

2) attribute values which are enumerated values (a fixed set of
keywords that are accepted and understood) may have, but do not
require, quote delimiters. Such as ALIGN="top" or ALIGN=top.

3) Within the CDATA defined attribute value strings ANY character
in the character set is valid, except the starting quote delimiter.
Therefore if the starting quote delimiter is: ', then the string
may contain a ", but it may not contain a '.

4) Character entities (such as Õ) and numerical character
references (such as &38) may occur in an attribute value that is
quote delimited.

5) Attributes that have the attribute name in parenthesis but do not
have a VALUE definition, have an implied value definition of the name
of the attribute if the name is NOT specified with the attribute.
Therefore, ALL attributes have a value, but minimized syntax allows,
but does not require, a value to not be provided if it is the same
as the attribute's name.

Of course a client parser needs to be as flexible as possible and
do its best to handle improper HTML or SGML syntax. But I want to
make sure my understanding is correct.

I am also having difficulty understanding the interpretation of
the FORM element METHOD attribute definition in the DTD. It is
defined as:

METHOD (%HTTP-Method) GET

where the HTTP-Method entity is "GET | POST". I am assuming that
my limited SGML knowledge is the problem here. However, all the other
attribute definitions appear to have #IMPLIED or #REQUIRED, except for
the ENCTYPE following METHOD.

Does this mean that GET or PUT are valid METHOD values, but only GET
is supported? It makes more sense for CDATA to have a fixed string,
but why have a list of keywords and then only allow 1?

thanks
Keith
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