Avoid the Line

Ursa Minor, Lumberjack, and I were having a conversation. (I love how often it's conversations that inspire my blogs.) For all I recall, this is an issue delt with a number of times over, but lets go at it again shall we.

Is there a defenition for "dating"?

When two people are said to be "dating", have they already kissed? Or is the kissing going to be happening within the next week?

Is interdigitation a requirement to achieve the state of "dating"?

If the word "exclusive" is added in, does that change the relationship or is "exclusive" already assumed with the original term "dating"?

Certainly I have my own vague defenition, but I'll wait a little while before I post my own ideas on the matter in order to keep other opinions as pure as is possible :) In other words, I don't want everyone trying to tare down my own theories.

However, one last quesion: What makes it so hard, socially, about moving out of "dating"? (Why can't people be friends after the brake up?)