the WebAssist validation variables you refer to come from the Server Validation Server Behavior.
In the Server Behaviors panel, you should have a server behavior named Server Validation
"Pass a url parameter in your failed redirect for your server validations like: pagename?valid=false"
In the server validation server behavior, there is a setting for Failed redirect. set this to redirect to the same page, and pass a query string variable, so if the name of the page is:
set the failed redirect to:
How do I translate this for my field value?
I can see that "yourdefault" could be "$row_eventset['club_organiser']"
this would be:
<?php echo(isset($_GET['valid'])?ValidatedField("page","field"):$row_eventset['club_organiser']); ?>
the validated entries code for your page will be generated from the bindings panel.
Go to the bindings panel, and expand the validated entries collection, then add a validated entries binding to your page, this will show the correct validated entries code for your page as a starting point.
If you are unsure of how to modify that code for the desired result, post it hear and i will be happy to help.