Thank You for all inputs /answers.
It's really nice to have such fast answers at all, and/but i have appreciated.
I realize that my questions where not implicating the reasons of my asking.
I had trouble after having
A) renamed the catalog (and by doing so introduced a misspelling in the totally-correctly renaming of the Smart preview and preview folders
and
having also strait away copied the whole "thing" from an external external HD back to my internal ssd hd
without having first checked if every thing worked
So i kind of panict and meanwhile LR had started building anew the Smart preview and preview folders (or one of them) without telling etc so i kind of got nervous..
Now everything is fixed.
Still find though that there is room to improve lightroom's management...
(wizards for all kind of procedures that a "genius-photographer might want to do.. ;-) )
Please let's not forget to remind ADOBE that they should never assume that we "by the time" all know everything by virtue of being used to it... when they further developp LR.
(elegance but transparency)
( i'm using LR almost daily since LR 1. ... )
Now i'm going to start a new thread for a question relating to how to create smart collection to automatically group/find (lost) print layouts (that had photos associated to it)
(I use LR in french so I mishandle the appropriate english terminology..)
Thanks again.