Difference between XML and XMI?

Question

Can some one shed some light on the difference between XML and XMI? Can XMI be used in place of XML?

Answer 1

The XML Metadata Interchange (XMI) is an Object Management Group (OMG) standard for exchanging metadata information via Extensible Markup Language (XML).

XMI integrates four industry standards:

XML - eXtensible Markup Language, a W3C standard. 
UML - Unified Modeling Language, an OMG modeling standard. 
MOF - Meta Object Facility, an OMG language for specifying metamodels. 
MOF Mapping to XMI 

http://en.wikipedia.org/wiki/XML_Metadata_Interchange

So XMI is a specific application of XML.

Answer 2

OK, let's try this again.

No, you cannot use XMI in place of XML. XMI is a specific use of XML.

XMI can only be used to exchange metadata information in accordance with the OMG standard. XMI is a specific application of XML. XMI can only be used for XMI purposes. XML, on the other hand, can be used for all XML applications, including XMI.

Answer 3

An XMI document is an XML document. An XML document is not necessarily an XMI document.

This is an XML document:

<myXml>
  <myTag> myContent </myTag>
</myXml>

but it is not an XMI document.

XMI is a specific XML dialect. It consists of a specific set of tags with specific syntax and semantics aimed at describing a model.