At the moment legislation does not stipulate any special procession procedure for electronic source documents.
Electronic source document may now be generated in any accounting system. Despite e-invoice, source documents at the moment have no united e-formats, that is why companies may interchange with any files providing that all participants of document flow can receive and read such documents (for example, Diadoc enables interchanging with documents in Word, Excel, PDF and any other formats). The fact the document was signed with e-signature is enough to weight it with legal force. Upon signing of the document by two parties it equals to the original with blue stamp. E-signature not only weights the document with legal force, it ensures the contractor cannot correct the document.