>>So, my question is: there is a way to save or to know the order of my index before change it?
>
>LOCAL lcOldOrder
>lcOldOrder=ORDER()
>SET ORDER TO lcNewOrder && lcNewOrder is your order
>...
>SET ORDER TO &lcOldOrder

Sorry, but the ORDER() function saves only the name of the index (or the name of the tag) but doesn't say if that one is in the ASCENDING or DESCENDING order. Unfortunately it's that information I need!