Looking for a 3dm file format description

I download the openNURBS toolkit but cannot find the file descriptionas mentioned here:

The openNURBS Initiative provides CAD, CAM, CAE, and
computer graphics software developers the tools to accurately transfer
3-D geometry between applications.

The tools provided by openNURBS include:

=====================>> A file format specification and documentation

C++ source code libraries to read and write the file format…

Is it possible to get the format description?

Thanks in advance

Hi Wolfgang,

Here is the “main” openNURBS page.


There is no “file format specification and documentation,” which may be why you don’t see it on this page.

I’m not sure what this means or what you are looking for. Can you explain further?

3dm-file format specification/description …

What information, exactly, would you expect to get from a format specification/description?

I have a file with 3dm-extension and cannot find out how to read it because the reader I found in the internet cannot read it or even crash. I would like to extract some data (readonly) but cannot find out how. The file seems to be a binary file as notepad++ shows.Some long time ago (now I am retired) I wrote FORTRAN- and Assembler-Filereader on Digital VAX/VMS having a great file format description of the files I had to consider, later on Sun Solaris using C and Perl. The file is test.3dm.

THANX Wolfgang

The file cannot load into Rhino, it gives an error message.
Looking at the file, the first three bytes read “PAK”. This is not a typical start for a 3DM file. It seems to suggest that it was compressed with Guardian Disk and Tape Utilities PAK compression utility, does that tell you anything?