Thanks: this is the function I was looking for. Unfortunately, I didn't find it under "See Also:" (for instance, under the help topic PRIMARY()).
>See SYS(2021) - Filtered Index Expression
>
>>...
>>Is there a function to tell me what the filter expression is?
>>
>>TIA, Hilmar.
Difference in opinions hath cost many millions of lives: for instance, whether flesh be bread, or bread be flesh; whether whistling be a vice or a virtue; whether it be better to kiss a post, or throw it into the fire... (from Gulliver's Travels)