FindBoundary is a String class function that examines the "content-Type" header specified in AContentType to detect the presence of a boundary marker parameter. If a boundary marker is present, it is removed from AContentType and used as the return value for the method. If a boundary marker is not detected, the return value for the method will be an empty string ('').
During message header processing, FindBoundary is used to retrieve the boundary marker that will be added to the marker list using Push.