This is a hook which is used (internally) to 'activate' filter validation.
This is our selection of topics, tagged "filter".
With this filter you can override the subject of the email sent to administrator(s) when a new (multisite) user registers.
With this filter you can override the default "New site created" email message.
Disable the action links shown below a custom form.
How can I stop a filter from outputting the default ?
You can either set a custom value through the admin or create a filter and return it false.
Validation of custom filters
The hooks we defined in the plugin, which are meant to hook your own output to, do not get checked on each load. You can however test them [...]