Learning Design from TAZ Design

I was trying to look at the design of the TAZ electronics enclosure to learn some design rules for an enclosure of my own. It looks like from the BOM you are using M3-.5 3.8mm Heatset Inserts and M3x5 Bolts.

I found the Electronics Enclosure directory and I saw the .STL file and .XOJ. What format is the XOJ? I tried to open it in Solidworks and couldn’t.

.xoj is just to create editable PDFs with xournal.