Scrolling doc bugs misnaming of scroll-up-conservatively

[Albatros Petrofsky]

>From (elisp)Textual Scrolling:

 - User Option: scroll-conservatively
     This variable controls how scrolling is done automatically when
     point moves off the screen (or into the scroll margin).  If the
     value is zero, then redisplay scrolls the text to center point
     vertically in the window.  If the value is a positive integer N,
     then redisplay scrolls the window up to N lines in either
     direction, if that will bring point back into view.  Otherwise, it
     centers point.  The default value is zero.

     A value of `nil' is equivalent to .5, since it centers point.  This
     variable automatically becomes buffer-local when set in any
     fashion.

I think that second paragraph is a bogus duplicate of part of the
documentation of scroll-up-conservatively.  When I do (setq
scroll-conservatively .5) I get Lisp error: (wrong-type-argument
integerp 0.5).  That's not equivalent to what (setq
scroll-conservatively nil) does.

 - User Option: scroll-up-aggressively
     
     The value of this variable should be either `nil' or a fraction F
     between 0 and 1.  If it is a fraction, that specifies where on the
     screen to put point when scrolling upward.  More precisely, when a
     window scrolls up because point is above the window start, the new
     start position is chosen to put point F part of the window height
     from the top.  The larger F, the more aggressive the scrolling.

Wait a minute....  I know this is all confusing, because the key
labeled "Page Up" is bound to scroll-down and vice versa, but if we
take emacs on its own terms, then "when a window scrolls up because
point is above the window start" doesn't make sense, does it?  To get
point from above the window to somewhere on the window, the text needs
to scroll down.  Shouldn't this variable be named
scroll-down-aggressively, and the documentation read something like
this:

 - User Option: scroll-down-aggressively

     This variable controls how scrolling is done automatically when
     point moves above the window start.  Its value should be either
     `nil' or a fraction F between 0 and 1.  If it is a fraction, that
     specifies where on the screen to put point when scrolling text
     downward.  More precisely, when the text in the window scrolls
     down because point is above the window start, the new start
     position is chosen to put point F part of the window height from
     the top.  The larger F, the more aggressive the scrolling.

Also, the interaction of the aggressive and conservative scrolling
variables needs to be documented, i.e. which takes priority?


It appears that, because of the high potential for confusion about
which way is up, most of the descriptions in this node are careful to
say "scrolls the text" rather than "scrolls the window".  Two
exceptions to this rule that should be fixed are in the descriptions
of scroll-margin and recenter.

-al