View-scroll-page-forward is an interactive compiled Lisp function in `view.el'.

(View-scroll-page-forward &optional LINES)

Scroll "page size" or prefix LINES lines forward in View mode.
Exit if end of text is visible and `view-scroll-auto-exit' is non-nil.
"page size" is whole window full, or number of lines set by
M-x View-scroll-page-forward-set-page-size or
M-x View-scroll-page-backward-set-page-size.
If LINES is more than a window-full, only the last window-full is shown.