Is an XML vocabulary a Domain Specific Language (DSL)?

Hi Folks,

If I create an XML vocabulary, then have I created a DSL?

Yesterday I heard someone say, "A configuration file is a DSL."

So if I create an XML-formatted configuration file, then I have created a DSL. Right?

Are there some XML vocabularies that would be considered DSL's and other XML vocabularies that would not be considered DSL's?

Is RSS a DSL? 

Is UBL a DSL? 

Is XSD a DSL?

/Roger