Online Export to Non EU at zero VAT, How to prove it to VERO

[raja1]

Hi

what kind of proofs are required by VERO if some online sales(software) are done from Finland to a non EU country at zero VAT rate.
Usually for the export of goods, one have to fill CN23 form along with Tulli web export registration as a proof for VERO.
But how will it work for selling an online service where no goods are involved.

Thanks