A certified true copy is a copy that a person with the required authority certifies as a true copy of the original presented to them.
The starting point
Ontario notaries can certify true copies within their authority. Commissioners for taking affidavits do not have a general power to certify true copies merely because they are commissioners.
What to be careful about
Bring the original document and the copy, or allow the notary to make the copy if that is the firm's process. The original must be available for comparison; a scan or photograph may not be sufficient for the requested certification.
How a lawyer can assess the issue
The organization receiving the copy may impose its own rules about who can certify it, wording, seals, dates, translation or authentication. Confirm those requirements before the appointment when possible.
Current Ontario context
If the document will be used outside Canada, ask whether an apostille, authentication or other destination-specific step is required after notarization.
Before a consultation
Bring the documents that control the issue and a short chronology of important dates. Avoid sending original documents or unnecessary sensitive information through a general website form.