Is there another way to scroll up?

[Water Lin]

In Summary buffer, while the cursor is on the topic, I can input SPACE
key to scroll down the article, and I can use DEL to scroll up the
article.

But I don't think the DEL key is very convenient to use. Can I bind the
scroll up operation to another key?

What's the key you are using?

-- 
Water Lin's blog: http://blog.waterlin.org