Private Function Nasob(ArcBId As Long, Id As Long,NumItems As Long, UserParams As Variant) As Variant

    Dim D2ObjData As VBApi_TUniVal

    Dim ret As Long

    Dim value As Variant

' Initiation

    If Id = -1 And NumItems = -1 Then

        On Error GoTo InvalidParams

        value = UserParams(1) * 2 ' testing the parameter, it must be a number

        On Error GoTo 0

        Nasob = RetOk

        Exit Function

    End If

    If Id = NoDataTime Then

        Nasob = "No data"

        Exit Function

    End If

    If Id = NoDataValid Then

        Nasob = "Invalid data"

        Exit Function

    End If

    ret = GetActualD2DataObj(Id, D2ObjData) ' getting the current data

    If ret = RetOk Then

        On Error GoTo InvalidEnum

        value = D2GetSpecificProperty(D2ObjData, D2ValueValue) ' getting the value

        Nasob = value * UserParams(1) ' multiply by 2

        On Error GoTo 0

    Else

        Nasob = "No data"

    End If

    Exit Function

InvalidEnum:

    Nasob = "Calculation has failed"

    Exit Function

InvalidParams:

    Nasob = "Ask for parameter Number"

    Exit Function

End Function