The lexical and value spaces of xs:string are the set of all possible strings composed of any character allowed in a XML 1.0 document without any treatment done on whitespaces.

This is the only datatype that leaves all the whitespaces. When whitespaces are not significant, xs:token is preferred.

The value of the following element:

Being a Dog Is
a Full-Time Job

is the full string "Being a Dog Is a Full-Time Job", with all its tabulations and CR/LF if the title element is a xs:string type .

The formal definition of the datatype is at: http://www.w3.org/TR/xmlschema-2/#string