The follow code snippet uses the PHP function strtotime and 4D's PHP EXECUTE command to determine the number of seconds between two ISO date timestamps:

C_LONGINT($0) C_TEXT($1;$2) C_LONGINT($o1;$o2) C_BOOLEAN($phpOK) If (Count parameters=2)    $phpOK:=PHP Execute("";"strtotime";$o1;$1)    $phpOK:=PHP Execute("";"strtotime";$o2;$2)    $0:=$o2-$o1 End if

If the code is saved in a project method named UTIL_SecondsBetweenISOdates it could then be used like this:

$t1:="2014-03-17T19:34:14Z" $t2:="2016-03-21T14:32:38Z" Alert(string(UTIL_SecondsBetweenISOdates($t1;$t2)))