bug#3517: 23.0.94; Emacs manual: <PageUp>, <PAGEUP>

emacs -Q
C-h r
 
C-s pageup C-s C-s...
 
Nodes                              Notation Used
----                               -------------
Moving Point, Completion Commands  `<PageUp>'
Minibuffer Edit                    `M-<PAGEUP>'
Scrolling                          `<PAGEUP>', <PageUp> (both)
Insert in Picture                  `C-c <PAGEUP>'
Key Index                          PAGEUP
 

Likewise, for pagedown. These two key names should be mentioned only
once, as synonyms for `<next>' and `<prior>', which are preferable
because the Emacs-Lisp symbols used for these function keys are `next'
and `prior'. In any case, we should not use one term (e.g. `<next>')
in some places and in other places use another term (e.g.
`<PAGEDOWN>'). That is confusing and impedes learning.
 
Also, sometimes we write `<prior>', sometimes (e.g. nodes `Scrolling',
`Completion Commands') we write `<PRIOR>'. We should be consistent.
We should always use `<prior>', both for readability and to reflect
the Emacs-Lisp function-key symbol, which aids learning.
 
Also, in node `Moving Point', `M-v' is written also as <M-v>. This is
non-standard, AFAIK.