The decimal representation of fractions of degrees. Many paper maps express coordinates in degrees, minutes, seconds (e.g., 40_30), where minutes and seconds are fractions of degrees. 30 minutes equal half a degree, and 30 seconds equal half a minute. GIS software, however, expresses coordinates in decimal degrees (e.g., 40.50 degrees), where fractions of degrees are expressed as decimals. Thus, the longitude: 40 degrees, 30 minutes, would be expressed in ArcView as 40.5 degrees.