Nodes Filter Variable Usage

I am trying to understand if it is possible to use variables, like ${Caption} in the Nodes Filter. I got this idea from writing custom resources for groups, similar to the ones in this thread Useful group custom SWQL query: Events on group members

Now I am wondering if I can use the same variables in other widgets in their filters.

Like below:

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mesverrum, tdanner  Any insight into this?

Thank you!!