created

This Campaign Item refers to Invoice Items which are either invoiced cancelled/cancellation invoices or not invoiced (yet).
Action to be taken: invoice invoices

open (Default)

This Campaign Item has no Invoice Items (yet).
Action to be taken: Create preinvoices

invoiced

For this Campaign Item all Invoice Items have been invoiced.
Action to be taken: Not applicable

canceled

For this Campaign Item, the Campaign Item has been either been cancelled or is a cancellation Campaign Item.
Action to be taken: Not applicable

irrelevant (Version 2.110 and up)

This Campaign Item has a connected item but no Invoice Items. This means that the item was cancelled or is a cancellation item but was never and does not need to be invoiced.
Action to be taken: Not applicable