There are a few ways to check if a property exists in an object. One way is compare it to the null value, for example:

var $myObj : Object $myObj:={A: 40; B: 25} If ($myObj.C=Null)    $myObj.C:=0 Else    $myObj.C+=1 End if

Another way is to use the command Undefined, for example:

var $myObj : Object $myObj:={A: 40; B: 25} If (Undefined($myObj.C))    $myObj.C:=0 Else    $myObj.C+=1 End if

Similarly, the command OB is defined can also be used, for example:

var $myObj : Object $myObj:={A: 40; B: 25} If (OB Is defined($myObj; "C")=False)    $myObj.C:=0 Else    $myObj.C+=1 End if

Note that an object property can also be assigned the null value, so comparison with null value could actually give a false positive when checking if the property does not exist. For this reason, using Undefined or OB is defined is a bit more precise.