This documentation is not using the current rendering mechanism and is probably outdated. The extension maintainer should switch to the new system. Details on how to use the rendering mechanism can be found here.
What does it do?¶
The PxValidation extension (px_validation) enables the possibility to define different validation configuration in your TypoScript for each Extbase-Controller-Action without touching the affected extension itself. This makes it easy to change the default validation behaviour of vendor extensions without changing their code. But the greatest benefit is that it opens the option to declare multiple variants of validation rules within one page tree. It is even possible to nest validation rules, so you can validate child objects.