Michael, I really want to thank you for this very useful teaching!

> like if you have a planar surface that's a rounded rectangle made up of lines and arcs and it's a standalone surface not joined to anything else.

Just out of curiosity I've done an experiment with that single planar srf you were talking about,
and I verified that happens what you told me.

After the "merge" command the single edge has changed its topology losing its internal structure.

I guess that, in general, this is not a desirable result.

> Personally if you have a structurally sound object I'd generally hesitate to mutate it by automatically doing these things
unless there was a lot to gain like if the edges were very badly fragmented or if the active area of a surface is very tiny compared to the full surface.

I understand now!
I will do as you told me.
That is, I will use the "merge" command only on restricted area and/or on very badly fragmented edges.

One last note.

I've experimented that it doesn't seem to be any relationship between "ShrinkTrimmedSrf" and "merge" commands.
That is, I've seen that the final result of the "merge" command isn't affected by the previous "ShrinkTrimmedSrf" command.
Or, at least I've seen this behavior in relation with the simple experiment on the "planar surface that's a rounded rectangle".

It this interpretation correct in general or does it differ case-by-case ?
I think for example to situations where I could run "ShrinkTrimmedSrf + merge" or only "merge" on joined surfaces...


Thank you very much again and have a nice day!

- Marco (mkdm)