عنوان مقاله [English]
نویسنده [English]چکیده [English]
The dual elevation system has been used in distribution of the North American Datum (NAD-83), with few people around the world aware of this, if they have previously heard about it at all. The application of this topic here is in fact as a kind of reminder, because there are many geodetic issues that are easier to access than this issue. This paper tries to state what this matter is, and why
we do need to use it.
Note: "The Canadian part of the Datum (NAD-83), which in some cases has been considered as different from the rest of the Datum parts, is not part of this discussion."