WMF stands for Windows Meta File.   EMF is a later (and more capable) version,
and though everybody should've switched to EMF, almost all the apps I know
support WMF better than EMF.

[VI] 2003-11-20 : I have done some work in writing a canvas out to WMF files.   
I think this is the best way to go to Staroffice and M$ office programs, also
the PDFs created from WMFs in Office docs are crisp and zoomable.  My code
isn't really publishable at this point, but the pointers to more information
are at:

http://www.saunalahti.fi/tlillqvi/gimp/wmf/wmf.c
Some commercial stuff at http://piet.jonas.com
A FAQ at http://www.companionsoftware.com/PR/WMRC/WindowsMetafileFaq.html
And of course the libwmf documentation at :
http://wvware.sourceforge.net/libwmf.html

My aim is to provide a towmf option which takes a canvas and coords as inputs
and generates the WMF, either as a file or as a string embeddable into RTF
documents.

If anybody has done work on this, do let me know