Canada Rules/Policies for Invoice Amendments in Canada

[Icarus1]

I would be grateful if anyone can tell me if there are any GAAP, SAPs, IFRS rules/policies within both Canada and the UK which states you can or cannot amend by hand the description on an invoice and sign and date the invoice prior to submitting for payment. For audit purposes both copies of the original invoice and the amended invoice (with signature and date) are held on file. No changes to the invoice costs.