What software package is your vendor providing? They are probably setting the parameter value automatically in their code and you would have to find some way to hook into that mechanism. So, you'll have to go to them to ask this question because we have no way of knowing how they've done this particular task through the SDK and what types of values they've set it up to accept.
If you can't do this through them then I may have another way of doing this:
1. Create a formula that is just a string value. In your example above, it would look like this (note the final comma on the end!):
{@Values}
"200,401,409,410,411,413,420,450,"
2. Create a formula to display this list correctly:
{@ShowValues}
left({@Values}, Length({@Values} - 1)
3. Change the If statement to this:
if InStr({@Values}, {pool_bearbeit.typ}) = 0
To update this list, you only have to change it in {@Values}.
-Dell