Does anyone know of a way to change a field to not allow changes to it once a certain criteria has been met. For example, if an invoice has been billed the "billed" field is changed to yes and no changes can be made to any fields within that invoice# but if it hasn't been billed then the fields are modifyable.

Thanks once again!

Well, you could do one of several things.

Set validation on each and 'EVERY' field to check if the invoice has been billed.

You could script each field so that if the invoice has been billed do not go into the field, else enter that field.

Or you could, if am invoice has been billed, script it so it goes to a layout that does not allow entry into the fields. This obviously requires tight control of your navigation from one invoice to another.

It is a pain in the posterior.

You can use access priviledges to only allow a user the ability to change records when a certain criteria is met (eg: billed = "no").