SunView is Sun's older window system and is not an X client. Together,
SunTools and SunView provide functionality similar to that provided by X
Windows and X Windows-based applications -- that is, SunView provides a
programming interface and basic windowing capabilities similar to X
Windows. But this system is NOT X Windows, it is Sun's proprietary
windowing environment, and is best thought of as a competitor to X Windows.
X is now the default window system shipping with new products (as of July
1990). Previously X was an unbundled product, available free from MIT or
available from Sun for a media and documentation charge.
XNeWS is Sun's X server that interprets X protocol and PostScript (NeWS
protocol). OpenLook is a functional specification for the "look and feel"
of the user interface (by AT&T). X clients generally use X toolkits (like
XView, XT+, OLIT, and so on), but they could simply make Xlib calls.
Thus, SunView is not an X Window System nor an X client; you can't display
it on MacX. If the Sun machine has the Xlib and applications, you should
be able to start one using a command similar to:
/usr/bin/xcalc -display mac:0,0
where "mac" is the Macintosh node name defined in the host's file.