Table A contains a column of values, and Table B contains a column of values that I want to constrain to only the values in Table A-via a popup menu or a validation rule (also missing from Numbers as far as I can find). It's likely I have not made my goal clear.

I get the Numbers paradigm and I like it, but I have failed to find a way to dynamically relate values in one table from values in another table for validation (popup menus) and conditional formatting in a sheet in Numbers.