I think you're confusing the two case types.

Have you looked at the pinned case type thread?

There is a clear difference between the clam shell and the digipak casetype, which has nothing to do with number of discs.

Link to thread warning large images ahead.

Quoting ya_shin:

Quote:
No, I don't think it has to have two discs inside to be a clamshell. As long as the two sides of the cover fold together and "hold each other tight" (lacking a better description), it's a clamshell.

This is correct. It's the "clamping mechanism" that makes it a clamshell and has nothing to do with the number of discs in the case. One side of the "Clamshell" fits inside the other, much like the old Disney VHS cases.

Quoting pgaudin:

Quote:
thanks for your help.

yes i've looked at the thread about cases. Aand when i look at clamshell fotos i don't see any mechanism to hold the two covers together when it's closed.
For me clamshell is a case which have only two parts (and not 3 parts .. or more like a digipack) .. like a oyster !!!!!
i have dvd with 2 parts (i don't talk about number of dvd in it: one or two) and no mechism to keep it closed... so if i understand wellyour explanations  it's also a digipack ... right ?

No.

I don't know how Disney released their VHS tapes in your country but if you had ever seen one released in UK, Germany, Canada, Australia, or the US, you would know what I'm telling you.

The Columbia House VHS releases of StarTrek: TOS were in those "clamshell" cases as well.

Quoting pgaudin:

Quote:
thanks for your help.

yes i've looked at the thread about cases. Aand when i look at clamshell fotos i don't see any mechanism to hold the two covers together when it's closed.
For me clamshell is a case which have only two parts (and not 3 parts .. or more like a digipack) .. like a oyster !!!!!
i have dvd with 2 parts (i don't talk about number of dvd in it: one or two) and no mechism to keep it closed... so if i understand wellyour explanations  it's also a digipack ... right ?

Yeah, I think you got it.

A simple test to determine what you have:

Take the DVD in your hands, holding it so that one side of the cover (front or back, doesn't matter) is facing upwards, so you can read it. Grab the topside with one hand, place the other under the backside. Now remove lower hand. If the box opens (and your DVD falls to the ground if not inserted properly ), you have a digipack in your hand. If it stays closed and the case looks similar to the above picture of "Lawrence of Arabia", you have a clamshell...

Thanks all for your responses ....
OK i see now what clamshell is (thans for fotos !!!) ... and i don't have dvd with clamshell box at home.
here in  France, that sort of case is rare.

it sems to me that clamshell was used by microsoft for dvds about developper ressources.