Search in list of pairs or dictionary

[math]

I have a structure as follows:
key1: A, B, C
key2: A, C, D, E
key3: D, E, F

Now I want to search for say value D and display key2, key3.

How do I implement this best?

Detail:
If the values are Apple, B, C and so on, it would be great to find “App” in Apple as well (as in the “contains text piece” block, but instead of true I would like the corresponding keys).

Hope it is understandable what I would like to do.

Thanks in advance for your help!

[ABG]

Here’s my take on this, using reusable filter procedures and a text-search-friendly data structure …

disct_search.aia (2.8 KB)

[SteveJG]

per ABG example:

[math]

Thank you very much for your very helpful and immediate answers!
Great!