Global Data for All Shaders

I know that Properties apply to a single shader. I was wondering whether there exists the concept of a global piece of information that can be set once and accessed by all shaders that need it. In particular, I want to use the player location to create a transparency cutout through objects between the player and the camera. Camera location, fragment location are fine. But to calculate whether something is visible or not, I need the player location. As several shaders may be involved, it would be a little inconvenient to set a player location for each object's shader every time the player moves.

 

http://docs.unity3d.com/ScriptReference/Shader.SetGlobalVector.html

 

Thanks! So do I declare the global in the Properties or is it something special?