Applications * astrometry * geophysics * orbitography * positionning IREP _http://hpiers.obspm.fr/eop-pc/_ (http://hpiers.obspm.fr/eop-pc/) Has anyone used them in a commercial application? I think I have an efficent method to include leap seconds however, but don't plan to program it until I know there is a need.. Anyone have ideas on how to notfiy the software to include or exclude leap seconds? Solution for including leaps seconds: Convert the year to binary value. If the months are the first quarter of the year mutiply by 4. If the months are the second quarter of the year Multiply by 4 and add 1. If the third quarter Multiply by 4 and add 2 If the fourth quarter Multiply by 4 and add 3 Us the binary result as an index into a table. Each postion of the table contains the cumulative binary leap seconds. Add the cumulative leap seconds to the seconds in the date. For every year the table will have four entrys per year. for 03-31, 06:30, 09-30 12-31 One bytes allows 256 cumulative seconds.