This extension supports CiviXero but has been written so that it could also support different accounting synchronisations in the hope it will encourage greater collaboration. It is a dependency of CiviXero
1) tables for storing event sync info - in particular civicrm_account_contact & civicrm_invoice_contact2) apis for storing data in these tables3) hooks civicrm_accountPullPreSave & civicrm_accountPushAlterMapped4) api invoice.getderived. This turned out to be a fairly important api as the line items for a given contact id are not easily retrieved. If the contribution is for a participant_payment then the participant entity rather than the contribution entity links to the civicrm_line_item table. I may not have used the best process to build this 'invoice' entity but it's a much better starting place for accounts interaction. It also resolves all accounting codes with is relevant for accounts interaction5) api to update civicrm contributions based on related invoice status6) api for cancelling payments based on civicrm_account_invoice - ie taking those items wherethe status in accounts is cancelled & not in CiviCRM. GOTCHA - cancelling an invoice via the API doesn'tcancel the event registraion - feature ? bug?