One thing that Hope doesn't seem to support are contentless elements. E.g. some drawing may look so:

    100:100:svg:svg
    100-100:svg:g /* group */
    100-100:svg:rect
    100-100:svg:rect

These elements have no text content, so their extent is 0 and offset is same. Yet they also have hierarchical relationships and you need to store extra data to express those. E.g. in this example you can guess that 'g' and 'rect's are descendants of 'svg' and the first 'rect' is a child of the 'g' but only because you have some preconceived ideas about the meaning of these elements. There's not enough data to tell if the second 'rect' is a part of 'g' or not. You need to store at least the level in the hierarchy. If you stored the data in a database (i.e. without implied order) you'd also need the relative position of the element, but here you have the order built-in.