Is there way to controll texture compression for iOS?

What PVRTC formats unity uses for diffuse/normal/lightmaps? Is there way to controll texture compression for iOS?
P.S Importing texture we can override format in Inspector. For iOS I only see 1) Compressed 2) 16-bit 3) True color. What corresponds to PVRTC2, what to PVRTC4?

Change the Texture Type to advanced to gain more control over import settings.

Read more about texture import here: http://docs.unity3d.com/Documentation/Components/class-Texture2D.html