Unlike a written document, the contents of which are fixed and can be read again and again, an oral presentation is ephemeral. Therefore, the standard of proof for ascertaining the content of an oral disclosure is high. Whether the amount of evidence provided is sufficient to establish the content of the oral disclosure based on this standard of proof has to be evaluated on a case-by-case basis and depends on the quality of the evidence in each case. However, evidence from the lecturer alone usually does not provide a sufficient basis for determining the content of the oral disclosure.