Understanding Mission Planner data log graphs

This post consists of several questions. When I pull up the data logs & its shown on the graph I need help understanding what it is I’m looking at. Its 3 sections in particular that I’m referring to. The Vcc…the RCin…the RCout. For each one respectively, what does the numbers on the side of the graph represent & what does the numbers on the bottom of the graph represent? What exactly is Vcc? Is that the total voltage being pulled from the lipo? RCin & RCout…I know C1, C2, C3, C4 are motors 1, 2, 3, & 4 but what exactly is RCin & RCout? Is it the voltage going in to each motor? The power output of each motor? Can someone please explain? Also, when I’m looking for voltage drops, specifically large voltage drops, what section do I look under & how do I recognize it? Thank you.

Read this:
http://ardupilot.org/copter/docs/common-downloading-and-analyzing-data-logs-in-mission-planner.html