What is the role of _Pvt_Extensions in LightSwitch

Question

In LightSwitch:

1. What is the role of the _Pvt_Extensions directory?

2. Why is it generally recommended that this directory should not be included in source control? Is the contents not necessary? Is it pulled from somewhere (where?) if it is not found?

3. Why is it recommended by Microsoft to include this directory in source control for Team builds (see How to Build LightSwitch Projects with Visual Studio TFS 2012 Team Build)?

Answer 1

When you click the box to use an extension, the files that LightSwitch needs for that extension are copied into that folder.

Not sure about the source control recommendations.