Because objects do not contain anything directly executable, it is theoretically possibile to change the files into something externally readable. Graphisoft is so good as to offer us an external converter for each version (since ArchiCAD 8.1), which converts single objects or complete libraries to xml files. These files can be edited with common XML editors. Binary items such as embedded pictures are transcoded into ASCII as old fashioned uuencode , much the same as was used for compressing and transmitting binaries by modems. If anyone can remember that far back. ;-)

The converters are available (in English language) as command line tools from the Graphisoft home page and is part of the Library Development Kit  You should make a point of keeping a copy of each version downloaded for future backwards compatibility, because there is only ever the version for the current ArchiCAD release directly available for download.

See Graphisoft documentation, download page and archive.

ArchiCAD 8.x also had the converter embedded and hidden in the special-menu.