How to set the doctype for your DotNetNuke skin?
There are 2 ways to force DotNetNuke to use an XHTML doctype:
A. Using an XML file
You can set the doctype for a specific skin by including a doctype.xml file.The name of this file should be: "skinname".doctype.xml.So for every HTML / ASCX file you will have to add an XML file.The content of this file should be:
<SkinDocType><![CDATA]<!DOCTYPE.....></SkinDocType>
The part should be replaced with the HTML doctype you want set.
XHTML 1.0 Transitional:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
XHTML 1.0 Strict:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
B. From the Host settings
You can set the Fallback doctype in host settings.Choose Host > Host Settings and select the doctype under “Fallback Skin doctype”.This will force all skins on all portals without a doctype.xml file to use the doctype you set.Please beware that this could potentially lead to unwanted effects if there are non XHTML skins in other portals then the one you are targeting.