Which of the following is a valid reason to set the Coordinate System parameter for the Microsoft Excel reader?

• A. The data will be viewed with a background map
• B. The data will be compared to other data in a different coordinate system
• C. The writer format requires a coordinate system
• D. All of the above

Answer: (D)

Setting the Coordinate System for the Excel reader defines how the numeric values in the sheet are interpreted as geographic coordinates. This is essential when you want to view the data on a background map, because the map and the data must share the same coordinate reference to place points correctly. It’s also necessary when comparing this data with other layers that live in a different CRS, since you’ll typically reproject to a common reference to make meaningful spatial comparisons. Finally, some writer formats require a defined CRS so the output carries the correct spatial reference information. Because each of these scenarios is a valid reason to specify a coordinate system, all of the above is correct.