Names are broken into two parts:
prefix - an identifier for a namespace
local name - an identifier for a name in that namespace
These parts are separated by a colon and called QNames (Qualified Names).
Example:
<c:pseudocode> <c:comment xlink:href="http://somewhere..."/> </c:pseudocode>
This applies only to element and attribute names.
Any prefix containing 'xml' is reserved for the W3C.