Hi, Kim.

I guess you already heard of the open Sdal format, but in case you didn't, would this be of any interest for you?

http://www.gis-management.de/update/sdal.htm

and

http://www.sdalformat.com

or

http://www.navtech.com/sdalformat/index.html

Thank you for your "work" on the matter...

Best regards,

Alberto