The programming language built-in to CSE HTML Validator (called TNPL) gives users a unique and powerful ability to customize the validation results by letting you create your own validation rules. With this programming/scripting language, customized programs can be written to check tags, attributes, attribute values, and more. These custom programs can generate custom validator messages based on the results of the checks.

Programs can be assigned to tags, attributes, and more, so that when a tag or attribute is encountered during validation, the assigned program for that tag or attribute is run to perform the checks.

For more information, visit the Language Syntax topic and the other sub-topics.