cbs\windowsbackup\url_rules.json

JSON data file Reference

A .json file contains structured data in JavaScript Object Notation, JSON. The format stores objects, arrays, strings, numbers, and boolean values as plain text. JSON is language-independent, and almost every programming language can parse it. Configuration files, web interfaces, and data exchange frequently use the format. The syntax comes from JavaScript object literals.

A file extension is only a part of the file name. It does not give a guarantee about the format or the content of a file. But on Windows, the extension selects the program that opens the file.