I understand now that posted transaction documents are not editable (except for custom fields). However, we have a couple of POSTED invoices that were done in error as we were learning to use the system. I had thought that there must be a way to void or rollback records in the system, or to create records that cancel the posted ones out, but there doesn't seem to be.
The only solution I can think of is to create a new picklist field that has an additional status for invoices, include a VOID option on that list, and then exclude all invoices with that value from reports, etc.
Any thoughts about this as a remedy? Any other recommendations for how to deal with this issue?