If you have a form that changes status from for instance "Draft", to "Completed", and you don't want the document to be editable once it is in "Completed" status, put the following form formula into the relevant view.
(MainForm is the 'editable' form, while PrintForm is the 'non-editable' form.) Users will only be able to view the documents using the 'PrintForm'. You can use this form in a print-formula as well.
@If(@IsNewDoc; @Return(Form); ""); @If(Status="Draft";"MainForm";"PrintForm")
- This does not accomplish its intended purpose. You can't depend on it to prevent document modifications. Author fields should be used for this purpose. —Andre