To run Validator, enter the following Usage: perl [options] This program invokes the SAX Parser, and then prints any errors to STDERR using SAX API.
It's good to develop an eye for clean XML code, which makes it possible to develop XML documents with a minimal amount of errors.
The downside to web-based validation tools is that they sometimes don't work well when you aren't dealing with files that are publicly available on the Internet.
For example, if you're working on an XML document on your local hard drive, it can be tough getting a web-based validation tool to work properly if the schema is also stored locally.
To do that, call https://validator.w3.org/nu/ or the URL for another instance of the W3C HTML Checker, and consult the following documentation: This section describes the behavior of each of the options exposed in the W3C Markup Validator user interface, and names of the corresponding query parameters (shown in parentheses) you can use with the W3C Markup Validator API.