maam to test understatement we need to check the completeness assertion, which involves tracing a sample form OUTSIDE the system through to its inclusion in the system.
however as far testing completeness of sales/trade receivables is concerned we check the GDNs and agree it to sales invoice through to its inclusion in the sales day book/TRs ledger.
now these GDNs are not from outside the entity, they are prepared by the entity itself, so then how is it valid?