The w3c working draft "Building a Tokenizer for XPath or XQuery" mentions a NotNumber. I can't find any references for this. What is this?
Reference: https://www.w3.org/TR/xquery-xpath-parsing/#DEFAULT_xpath
There: "2.1.2 XPath Lexical States"
The first table matches the pattern "NotNumber" amongst others. Is this like the IEEE 754 NaN?
The same question is about NotOperatorKeyword, which also does not have a reference.