Since my blog post the other day there have been a number of emails/posts with various questions, so I thought I'd aggregate the answers here to help those curious about further details.
Q. Now that skins support dynamic doctypes, will my existing skins work, or do I need to create the new xml file for skins to work?
A. No, if theres no xml file, then we will continue to use the legacy doctype declaration, so you don't have to make any changes to your existing skins.
Q. Why did you do it this way?
A. Originally I planned to use the existing skin.xml file to store the doctype definitions and store the details in the skin table, but ended up going off the idea due to the effort involved in parsing the details, and the impact on the code. In addition I didn't want to break any of the tools that work with the skin.xml schema such as this. Next I considered parsing the htm/ascx pages during upload for DOCTYPE declarations and storing the details, but found a recommendation not to declare DOCTYPE's in ascx files due to the possibility of multiple declarations being combined when the fragments were combined. Whilst the skinning design of DotNetNuke should ensure that this didn't happen, if someone uploaded a skin declaration as a container it could cause a crash. The final solution of having an optional file per skin supported the desire to preserve backwards compatibility, not break existing tools and allow skin developers to ship different versions of skins with different declarations in the same zip e.g. an xhtml 1.1 strict version of a skin for intranets and a html 4.0 transitional version for internet usage.
One point to note is that the main change was making the doctype a server variable, how you choose to change it is up to you. The default method is using the skin level xml file, but you could also do it via code.
Q. I've looked at your code, and it looks like it was written by a drunken monkey?
A. Thats true, it's definately version 1.0. I'll be tweaking it to use the xmltextreader rather than the poorer performing xmldocument. It's really legacy code from an early test version where I was playing with validating a single xml file, and using XPATH to read the values. In addition we'll be caching the details to make it more performant. I was caught out by the xmas holidays, and didn't get a chance to make the changes before 4.4 was released.
Q. Is this the final implementation?
A. No, I'll be tweaking it as above, and there have also been requests to have a single file that would declare the same doctype for all skin files in a folder e.g. a single doctypes.xml file that would apply that declaration to each skin.
Q. Are there any other compliance changes lined up?
A. Absolutely. At present I'm sourcing a css-based, tableless skin that can then can be used as a reference example (it'll probably use the tableless version of the dnnmenu ) as well as help us test the various compliance standards. In addition there are a number of other tag fixes, and access key support to be checked in. At that point, we'll then be ready to look at core modules and suggest changes to the project teams.
Finally, I'd like to acknowledge the help of community member, David Wendelken, who volunteered his help and submitted some needed changes.