FT_ELTIME()
 Compute difference between times in hours, minutes, seconds.
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 Syntax

      FT_ELTIME( <cTime1>, <cTime2> ) -> cDiff

 Arguments

     <cTime1, cTime2>  character strings representing times in
        hh:mm:ss format.

 Returns

     <cDiff>  character string representing time difference in
        hh:mm:ss format.

 Description

     Return the absolute difference between two times in hh:mm:ss format
     in character hours, minutes and seconds (hh:mm:ss).

 Examples

     FT_ELTIME( "22:40:12", "23:55:17" ) -> 01:15:05
     FT_ELTIME( "23:55:17", "22:40:12" ) -> 01:15:05

 Source: ELTIME.PRG

 Author: Alexander B. Spencer