Returns the local part of the name of $arg as an xs:string that will either be the zero-length string or will have the lexical form of an xs:NCName.
If the argument is omitted, it defaults to the context item (.). The behavior of the function if the argument is omitted is exactly the same as if the context item had been passed as the argument.
The following errors may be raised: if the context item is undefined [err:XPDY0002]XP; if the context item is not a node [err:XPTY0004]XP.
If the argument is supplied and is the empty sequence, the function returns the zero-length string.
If the target node has no name (that is, if it is a document node, a comment, or a text node), the function returns the zero-length string.
Otherwise, the value returned will be the local part of the expanded-QName of the target node (as determined by the dm:node-name accessor in Section 5.11 node-name AccessorDM. This will be an xs:string whose lexical form is an xs:NCName.