For e.g. post 195, we have a URL such as http://HOST/BLOG/195/post.xml, and this XML file has an "<html>" element, e.g. "<html>My post contents<div class="postTools"></div></html>"
Where there is attached data on a post, if a 3rd party client wants to display that, it currently looks like it is necessary for the client to look in post.xml for the "<attached_data><data>http://HOST/data/DATA.xml</data></attached_data>" section, then retrieve and parse all the DATA.xml files returned, in order to find the <dataitem> elements that finally give links to the attached data.
Could these links either be added to the existing <html> element, or a new element e.g. <linkedhtml> introduced whose content would be that of the existing <html> element but with the links to each attached data item appended, so that there is not a need for every client app to follow the current, and somewhat longwinded, process to give its users access to attached data?