Data Validation List Avoiding Displaying Same Values

Hi,

I'm struggeling with dependent data validation. I'm trying to build up categories through lists with each column depending on what was selected previously.
The problem is tha I have to repeat vlues to enable the next selection.

Maybe this is not (probably not) the way I should do this thus any other way is welcome.
I've tried naming arrays, index and match (as in the attachment) but without succes.

Any ideas?

Thanks in advance.

Best regards,

Steve.

Thanks.

But how to deal then with when example SRQ is also used by others (CP,CS,...) and having different lists items eather?

E.g. CP SRQ x
y
z

CS SRQ a
b
c


Best regards,

Steve.

Well that's the problem. They are different.
But thanks anyway.

Someone else an idea?

Thanks in advance.

Regards,

Steve.