excel xlsx is just an ordinary zip file contains xml files. Nim standard
library already provide an [xmlparser](http://nim-lang.org/docs/xmlparser.html)
module to read xml files and converts it into XML tree representation.
to be able to read zip file, there is a [libzip
wrapper](https://github.com/nim-lang/zip) to do this kind of job.
using xmlparser and libzip, you can read and write xlsx without COM.
if you want to study the xlsx format, extract the xlsx content with any zip
extractor and read those xml(s) with your favourite text editor.
no need of any COM and you'll be able to read/write/manipulate excel xlsx.
