Function of page up/page dn in scrivenings mode

[RC7] I’m having trouble understanding the navigation keys in composition mode, using scrivenings. Obviously this is the mode one would want to use to most closely approximate the behavior of a word processor, where only the text of the document is showing, and the reader is reading and editing the story sequentially.

Normally, when using a word processor like Word, pressing the “page down” key would display the next screen’s worth of text on the word processor screen. So, if one is reading the story, one screenful at a time, page down takes you to the next screen of text.

Not so in Scrivener. Page down takes you to the end of the current document or file, and then, the next file. Which is fine, I suppose. But what key combination will display the next screenful of text? Pressing the down arrow key to scroll downward is tedious at best. Surely there is a single key that can be pressed to see the next screen’s worth of text.

What is it???