Steps to reproduce the issue

I was looking for a fields plugin event called when an article using customs fields (com_field) is saved.
I found FormModel::validate() function triggers onUserBeforeDataValidation event.

Adding function onUserBeforeDataValidation($form, &data) to my field plugin produces the functionality I require.

Expected result

(a) Documentation for the onUserBeforeDataValidation event
(b) A more meaningful event name e.g. onFormModelBeforeDataValidation

Actual result

(a) I could not find any documentation for this event
(b) Looks like original author for this event was too focused on the user problem they wanted to solve and not thinking of the wider applications of this event.

System information (as much as possible)

Joomla 3.8.4

Additional comments

Suggest changing FormModel::validate() function to something like the following:

if (get_class($this) == 'UsersModelUser') {
// Obsolete, kept here for backward compatibility
$dispatcher->trigger('onUserBeforeDataValidation', array($form, &$data));
}
$dispatcher->trigger('onFormModelDataValidation', array($form, &$data));