Collada 1.4.1 animation

Hello.
I’m trying to import a .dae file to my C++/OpenGL application. I’ve got per each <animation> five sources:
[ol]
[li]Input.[/li][li]Output.[/li][li]Interpolation.[/li][li]Intangent.[/li][li]Outtangent.[/li][/ol]
One <sampler> and one channel. The question is: What does those five sources mean? What do they do?

Edit: Found.