i am new to this forum and I noticed that there is a calpos routine going around . Having looked at the code, I have some concern. It seems that the program is assuming the earth is spherical , ie constant radius. MP is clear about actually using a WGS84 ellipsoid. The error then can easily reach several hundred of meters if using a spherical assumption. Anybody has concerns about that or I am actually wrong? Has anybody checked how MP actually computes distances between 2 points? Thanks.