Why isn't my test playlist added to the *.vsmdi metadata file in visual studio 2012

Hello and thank you for your time,

So here is my problem:

I want to write a batch file to schedule the launch of my tests in Visual Studio 2012 using this command:

MSTest /testmetadata:TestProject1.vsmdi

And so I want to include a specific set of tests in my batch file. To do this I created a playlist on Visual Studio 2012, but this playlist isn't generated in my metadata *.vsmdi file. With Visual Studio 2010 I used to create new Test Lists which were automatically added in the metadata file, but in VS2012 I just can't find them.

Is VS2012 Playlists different from VS2010's test Lists?

Can I even use my created playlist with the MSTest command line?

Thank you