I am guessing that you want to "Commit" that invoice then later, want to prevent a future change.....
You can set a new "Commited" Status field the you can compare with future attempts to change that useing "OnObjectEnter" script. The Object being the Status Field the User set. I call the new field say... Commited Status.
So when the Usert changed it to "On Order" your script would compare Commited to User and sends an Error message and resets the User Field back to "Recieved"
You can set validation calculations in field options on each field you want to lock that reject all input if the status field = "received".
- You can move the three fields into a related table and then user record level access control to block changes to the invoice record (and maybe a set of line items records?) while the three fields no located in a related table remain editable. See "Editing record access privileges" in FileMaker Help and check out this particular sub section: "Entering a formula for limiting access on a record-by-record basis" for a description of how to set this up.
- You can set validation calculations in field options on each field you want to lock that reject all input if the status field = "received".