This article is from the Geographic Information Systems FAQ, by Lisa Nyman lnyman@census.gov with numerous contributions by others.
From: tchild@AUTODESK.COM (Timothy Child)
DXF(R) is the Drawing eXchange Format from AutoCAD. The definitive
documentation for this format is in the current AutoCAD Release 12
Customization Manual. I believe that a copy of the DXF appendix is also
posted on the Autodesk Compuserve forum. Try contacting the Autodesk
Australian office for details on this:
9 Clifton St.
P.O. Box 458
Richmond
Victoria 3121
Phone 429-9888
Another good reference for the DXF format is provided in:
The AutoCAD Database Book
Authors: F.H. Jones and L. Martin
Published by Ventana Press
ISBN 0-940087-04-9
Ventana Press may be contacted at:
P.O. Box 2468
Chapel Hill
NC 27515
USA
Phone (919) 490-0062
Also, Virginia Hetrick, in sunny Calififornia <IARGRAF@MVS.OAC.UCLA.EDU>
suggests:
Kay, David C., and John R. Levine (1992) Graphics File Formats.
Sorry, I don't know either the ISBN number or the publisher since
I just got an ad with the book identified in it and it specifically
says that it contains a description of DXF formats. I'd suspect
that this one is probably more readily available in libraries than
the others.
WWW resources:
A page of links:
http://wwwis.cs.utwente.nl:8080/faase/DWG/dxf.html
Release 13 documentation in Windows Help format
with a supplementary browser to simplify searching:
http://www.cloudnet.com/~dyoung/
Release 10 documentation in text format:
ftp://ftp.cc.monash.edu.au/pub/graphics.formats/DXF.ascii.Z
 
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