Type and Creator Codes, gzip, and bzip2
In Tiger, if you use gzip or bzip2 to compress a file, the archive is given the same type and creator codes as the original file. This is a problem because double-clicking the file in the Finder will not decompress it with BOMArchiveHelper. Instead, it will try to open the file with the creating application, which will complain that the file is unreadable. One remedy is to use Get Info to make the file open with BOMArchiveHelper. An upcoming release of DropDMG will address this issue for .gz and .bz2 files that it creates. Of course, this is not a problem for files that you share over the Web or FTP, since uploading the file will clear its type and creator codes, and then it will once again open with BOMArchiveHelper, StuffIt Expander, OpenUp, etc.
