What is the definition of "undetected" in Metal Gear Solid: Ground Zeroes?

I am really trying to complete the "Like a Boss" Xbox One challenge: Clear all missions (NORMAL and HARD) within the time limit without being spotted and with 0 kills.

In order to achieve undetection do I need to be completely unseen? That means:

• No white-arc warning on screen,
• No radio communication between guards ("CP, this is Zulu X, I saw a suspicious figure, going in to check out."
• Status alert remains Normal,

I keep on restarting the mission not knowing whether I have or have not compromised the challenge.

Please specify what criteria I need to follow to be "undetected".

From my experience with Ground Zeroes

Undetected is when no one knows you are there. Let me explain:

If an enemy sees you but it doesn't activate reflex mode (normally the white-arc on the screen appears) you are still undetected!

If the Reflex Mode is activated you must take him down within the reflex or you will become detected. For your challenge specifically you can't kill him since the challenge requires 0 kills. If you succeeded in taking the enemy down you will still be undetected!

While I was playing if they find bodies of other soldiers you will become detected. I once forgot a body on the floor and didn't think they would care but if you give them time, they will call CP for support depending if the body is from a dead soldier or a knocked out soldier.

I hope I was able to answer your question the way you wanted.