Re: [dita] clarifying the href attribute in the language reference

["Eliot Kimber" <ekimber@innodata-isogen.com>]

Grosso, Paul wrote:
> 
> Yes, and we should note that implies certain character
> restrictions, and we need to say something about what
> should happen when the value isn't a valid URI (even
> if we leave that implementation dependent).

I'm not sure I understand why we have to say anything about invalid 
URIs--they're invalid and processing should fail.

I suppose the other alternative would be to say that processors should 
do whatever they need to make the value be valid (e.g., escape any 
disallowed characters). This is admittedly a fuzzy area in XML.

I think that Paul's concern is that within a tool like Arbortext Editor, 
where you will be creating links to local files, is the tool obligated 
to escape characters that are valid to the file system but not valid 
URIs? My take would be that they should be escaped--I think systems that 
pretend that non-URI syntax is OK (e.g., using something like 
"c:\foo\bar.xml" where a URI is required) are doing everyone a 
disservice. But maybe that's just me? It doesn't help that most XML 
processors will silently accept "c:\foo\bar.xml" as a URI--that's a 
convenience but not actually in line with the requirements of any 
specification (including XML) that says a value is a URI or URL.

>> * A URI with a hash must have a valid DITA local identifier 
> 
> s/A URI with a hash/An href value containing a hash/

I think it should be "A URI with a fragment identifier"--fragment 
identifier is the abstract URI component and that's what we really care 
about. The spec should not be and does not need to be a tutorial on how 
to construct URIs. It needs to be as precise as it can be.

Saying "an href value containing a hash" is ambiguous since an escaped 
hash character is both valid and, in the context of URI resolution, also 
counts as "containing a hash" that, because it is escaped, is not the 
fragment identifier separator.

>> as the portion after the hash. A DITA local identifier 
>> consists of topicID/elementID for a subelement of a topic and 
>> of elementID for topics, maps, and map subelements.

c/local identifier/fragment identifier/

>> As long as we're nailing down the description of href, are 
>> there any special considerations having to do with IRIs [1]? 
>> I wouldn't expect so, but I have a shallow understanding of 
>> IRIs and translation issues in general.
>> [1] http://tools.ietf.org/html/rfc3987
> 
> There could be.  (I was hoping to avoid this question for
> the sake of simplicity, but it is actually a good question.)

I think we should avoid IRIs and HRRIs for now.

Cheers,

E.
-- 
W. Eliot Kimber
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