XForms CR - 7.10.1 - The argument to the instance() function

It seems to me that there is an inconsistency in the description of the 
instance() function.

In the first line of 7.10.1 it is indicated that the argument to instance() 
is a string. I assume that is an XPath 1.0 string, rather than say an 
xsd:string, but that could be made clearer.

However, 7.10.1 goes on to say, "The argument is converted to a string as if 
by a call to the string function.". Which seems odd if the only allowed 
argument *is* a string.

The argument can't be a number. The value of an id attribute is not permitted 
to start with a numeric character.

It seems unlikely that the argument will be a node-set or boolean.

Can the sentence, "The argument is converted to a string as if by a call to 
the string function." just be deleted?

Andrew Watt