The javascript for multicart HTML exports look like this:

var _cartname=[`title.p8`, `level1.p8`, `level2.p8`, `level3.p8`];
var _cdpos=0; var iii=0; var ciii=0;
var _cartdat=[204,204,204,204,204...]

All the carts are stored in the _cartdat array. How is each cart stored in that array? Is it a fixed number of bytes, or some other method? E.g. some kind of end marker indicating the end of a cart?