Thanks @vitor I've added an almost identical script filter so that I can use "gst" as a keyword for either inclusive or exclusive. I've already learnt quite a bit about how each part of the workflow contributes to the outcome thanks to your solution which is relevant to my tasks. (Among other things) I didn't understand how to set the prompt text for each result until now so I'm very happy with this.
Hmm. It occurs to me that this is integer values, not float / double. I'll investigate further