Before beginning, it is recommended to read the article FAQ: Projection Basics: What the GIS professional needs to know to understand the parameters required for various coordinate systems. This article also has useful information about working with coordinate systems in ArcMap.The general procedure for.identifying an unknown projected coordinate system is described in the article How To: Identify an unknown projected coordinate system using ArcMap, and How To: Identify an unknown projected coordinate system using ArcMap 10.1 and later versions. However, those instructions assume that the area of interest is within the United States (USA). If the the area of interest is outside the USA, the following guidelines are provided.
Note: If this procedure in unsuccessful, an alternative is to create a custom projection file. Please see the following article: How To: Create a custom projection file with units of feet or meters in ArcMap
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