How to sum up things in layer?

HI all,

do you have any idea how to sum up items collected in layer?? Imagine situation when the layer is build with rule that collects bend_note feature. Every time when new bend feature is created, it is added to the layer. There is no problem to create such layer.
It would be great, to store it as parameter (bends_qty).
It could be useful to calculate time needed to produce sheetmetal part (bends_qty*time_for_one_bend).

I know that there is an info accesible for the layer, but it is shown only as a note.

Any idea??

regards,
Krzysztof