Head and shoulders, and the inverse

Which of these is required for a head and shoulders top?

• A prior uptrend and a middle peak higher than both shoulders
• Three peaks of equal height
• A flat neckline

The neckline slopes upward. Why can't you judge a break by comparing the close with the first reaction low?

• Because upward necklines are never broken
• Because the line keeps rising, so on the break bar it sits above both earlier lows
• Because you should use the second low instead