I wish to create a custom template for approvals, however I am having some trouble finding where in the documentation it specifies the name of the merge fields related to the approval such as those to generate the link, all I could find was this reference in the online help "If the email template you choose contains approval merge fields named {!ApprovalRequest.field_name},..." but it does not specify what the field names are for the approval request.

Know where I can find more information.