These and many other commercial free data sources use the spherical Mercator data projection (identified by European Petroleum Survey Group [EPSG] code 900913).
这二者以及很多其他的商业的免费数据源都会使用球形的Mercator数据投影（由EuropeanPetroleumSurveyGroup [EPSG]code 900913 标识）。
Thompson's projection used a day-by-day count to cross -reference the Mayan to the European calendar rather than a count of years.
汤普森的设想是作用逐天计算去勾划——涉及了玛雅到欧洲的历法，而不是年的计算。
Thompson's projection used a day-by-day count to cross -reference the Mayan to the European calendar rather than a count of years.
汤普森的设想是作用逐天计算去勾划——涉及了玛雅到欧洲的历法，而不是年的计算。
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