How do you tell if a design is FSL or just plain lace? I have so many designs that were downloaded, but not labelled properly at the time.

oh you are just like me lol
I am going over my old designs and trying to
label them correctly.. before I began placing designers initals to the front of files..
Shirlene and Mops have given fabulous advice
sometimes the high stitch count can tell you
but for me unless it says fsl in the file I take it as a lace design :-)
Big hugs from London - Maria xx

Lyn, I agree with Martine - it is difficult to tell - a good program that allows you to do a simulated stitch - can't always show if the design totally connects - if you know the names and the designer - we could possibly help you that way or you could just email/contact the designer and ask. I have alot of lace designs - that when I bought them - thought they were FSL and they are not - we all can get fooled. I don't think it is intentional on the part of the designer - but most of them do specify FSL if it is.

If I can assist you - please let me know - I must know a big share of the FSL designers on the web.

That's difficult.
As a rule you'll see more than one layer of stitching at different angles in FSL, but there might be specially digitised stitches that hold together well even in one layer (I used those in some of my Christmas ornaments).

I would have a close look in my software, zoom in and see if there are areas that look unconnected.

If you don't have that possibility, the only thing you can do is stitch them on a layer of organza or (bridal) netting and have a very close look at the stitched out article - not full proof, but it's the only thing I can think of!