confused about "double attachment" setting

[brynn]

Hello,
I used SMF several years ago, probably under 1.1x, so this is a new setting which I find confusing.  It's this one:

"Do not show attachments under the post if they are already embedded in it."

To me, an embedded image must already have a URL before you can embed it in the message.

An attachment has no URL, until you attach it, when it gets uploaded to the website's server. That gives it a URL. But then, there is no need to go back to the message box and embed it.

I checked the online manual, but this setting does not seem to be explained (https://wiki.simplemachines.org/smf/SMF2.1:Attachments_and_Avatars)

I also searched the forum, and it looks like when you embed an image, apparently it also shows up as an attachment.  I just don't understand why.  To me, these are 2 separate things, which have apparently been intermingled.

If the only thing this setting does is prevent the embedded image from showing as an attachment, I wonder why it would show as an attachment at all. So it seems like there must be some new kind of definition regarding either embedded or attached images, or how they are handled. But I can't quite make the leap.

Would it be possible to explain what's happening with this, without getting too technical?  Or is it really a very technical reason?  Possibly related to new PHP or HTML standard - something like that maybe?

Thanks for your patience?
Edit
Sorry, I've forgotten my manners.  We're using SMF version 2.1.3. No mods added yet. The site is not even online yet.  Looks like I better edit my profile too....  Thanks again.

[Aleksi "Lex" Kilpinen]

What that setting does, is remove the thumbnail image from showing under the post if the same attachment is already embedded in the post.

You cannot view this attachment.

So the image above WOULD show. The attachment info below would NOT. 2.1 attachments get uploaded before the post is made, so this is possible.

[brynn]

Are you saying that the new feature (new to me, I mean) is that attached images are actually embedded in the post?  I don't recall that they ever showed within the message.  I only remember they showed below the message.

Thanks!

[Aleksi "Lex" Kilpinen]

The most significant changes are that when you are making a post, you need to upload the image before you publish the post. This also gives you an embed code automatically, so you do not need to form one yourself afterwards. If you use this embed code inside your post, you can do what I did in my earlier post without editing the post at all.

Try it out, experiment - I'm sure you'll see what is different

[lurkalot]

brynn

I after you choose your file, click upload.  You then have two choices. 

You either click insert then post which will add the image inline in the post itself, or

You click upload and post without clicking insert and it will add the thumb underneath the post like it did in 2.0 (assuming you haven't disabled the thumbnail)

[brynn]

Ok, I see it now.  The new feature is the option to insert/embed the attachment before posting.

I guess it's a way to have the attachment showing within the message?

Yes, I do recall how awkward it was to have to number and label the attachments, and refer to them within the message, when you need to show a few images.

Thank you very much!

Edit
Hi lurkalot (Mick, iirc?) -- I remember you always had a talent for posting while I was typing.  And I see you are still at it!  It's good to see you again! I think it was actually a 1.1x version that I was using.