What is the Disney kiss rule?

Can you elaborate on the so-called "Disney kiss rule"? It sounds intriguing, as if it's a guideline for romantic scenes in Disney films. Is it a strict code of conduct that all Disney productions must adhere to? Are there any specific criteria or conditions that need to be met in order for a kiss to qualify under this rule? And finally, how does this rule influence the storytelling and character development in Disney's animated features?