Apple Numbers application and format.

Hi.

With a little help in IRC (Thanks) I managed to convert a ods (calc) file to apple's number 
application using .xlsx as an intermidiate format.

Does anybody know, where I can find a specificition of the numbers file format ?

if the format is known, it cannot be that hard to write import/export functions, and my time would 
be better spend than converting file formats.

thanks in advance
rgds
jan i.


Sent from my iPad, please excuse any misspellings