Is <:nodename> a valid xml node name?

Question

I read milions of questions about xml node naming rules. But none of them answer the simple question: Can the node name start with colon?

Example:

<:nodename>Inner text</:nodename>

This can be associated with empty namespace (global namespace). But not sure if this is valid, and what is the possible usage of such a name.

PS. No real application of code, or ideas where to use it, just curiosity and self-learning purposes.

PS 2. Some research links:

• this one: http://www.xmlvalidation.com says it is wrong (but it cannot be trusted I think)
• https://stackoverflow.com/a/2519943/1125465 (great answer btw) says it is ok
• http://www.w3.org/TR/REC-xml/ - The Namespaces in XML Recommendation [XML Names] assigns a meaning to names containing colon characters. Therefore, authors should not use the colon in XML names except for namespace purposes, but XML processors must accept the colon as a name character. Still no answer...

Answer 1

It's well-formed according to the XML 1.0 and XML 1.1 specifications, but not according to the namespaces specification. Most people (and software) require XML to be namespace-well-formed, so it would be definitely best to avoid it.