In this tutorial, you’ll become familiar with the Fleet Management Extension model.
You may require that certain text fields not be zero-length, that a field be formatted as a telephone number or other type of well-formed data, or that a string not contain any unsafe characters that could be used to compromise the security of a database.
though: The Error Provider component does not provide built-in support for accessibility clients.
To make your application accessible when using this component, you must provide an additional, accessible feedback mechanism.
When you submit a form to a CGI program that resides on the server, it is usually programmed to do its own check for errors.
If it finds any it sends the page back to the reader who then has to re-enter some data, before submitting again.