Where is cl_context defined?

I just find a typedef for it in cl.h, cl.h includes only CL/cl_platform.h, but I cannot find it there. Also the documentation [1] does not say much about it.

[1] http://www.khronos.org/registry/cl/sdk/1.0/docs/man/xhtml/abstractDataTypes.html

cl_context is an opaque type, you wont find a proper definition unless you are writing a OpenCL icd… You just pass it as a handle to the appropriate API functions.