Касательного самого xml 1.1 (чтобы не возникало вопросов, что это такое) : 

Everything you need to know about XML 1.1 can be summed up in two rules:

    Don't use it.

    (For experts only) If you speak Mongolian, Yi, Cambodian, Amharic, Dhivehi, Burmese or a very few other languages and you want to write your markup (not your text but your markup) in these languages, then you can set the version attribute of the XML declaration to 1.1. Otherwise, refer to rule 1.