Stupid question: Is it possible to create a scheduled transaction with an unknown value

[Raphaël Maville]

Is it possible to create a scheduled transaction with an unknown value ?

I mean, when you know you will have to pay something a day in the
future, but you do not know how much yet: how to ? possible ? instead,
use a previous one or estimate one (some are hard to estimate before
they occur) ?

Thanks.