The status of an invoice can be any of the below values. Note that the distinction between quotation and invoice is purely done by status. For example, the record may be a quotation initially and then, by status change, move to being an invoice.
The invoice is under preparation
The document is a quotation and sent to client or supplier.
The quotation was accepted by the other party.
The invoice is under preparation.
The invoice is sent to the client or supplier.
The invoice was paid.
The invoice has an issue and needs to be reviewed.
The invoice is approved.
The document is cancelled.