The namespace http://www.w3.org/2005/xpath-functions/json is used in the combined XSD in C Schemas:

<?xml version="1.0" encoding="UTF-8"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
    elementFormDefault="qualified"
    targetNamespace="http://www.w3.org/2005/xpath-functions"
    xmlns:j="http://www.w3.org/2005/xpath-functions/json">
    
    <xs:include schemaLocation="analyze-string.xsd"/>
    <xs:include schemaLocation="schema-for-json.xsd"/>
</xs:schema>

I don't think it hurts being there, but I can't see that namespace referenced anywhere, in fact, I think it ought to be "http://www.w3.org/2005/xpath-functions".

The referenced schema, schema-for-json.xsd, and the body of the text on the relevant functions, uses the namespace http://www.w3.org/2005/xpath-functions instead.

I think it can be dropped.

Part of ACTION A-654-11.