Written into every header and checked when one is read. The format is expected to grow - a header is cheap to extend - and a file from a later Issie should be refused with something better than a decoding error. .dgm has no version field, which is why loading one is three decode attempts in sequence; this is the one chance not to repeat that.

catalogue section used when a component does not name one

directory under static/ holding the libraries shipped with Issie