Full packages are backed-up seperatly from the root, and expanded at boot time. Addon's are things to small or simply for a full packages. Usually they just contain one or two binaries. They contain several files that are nessary for the root utilites to properly manage and back-up the package. At all times, in all text files, make sure to end the file with a newline.
All packages are gzip'ed tar archives.
The must follow the 8.3 naming scheme for FAT compatiblity. The ending extension MUST be .lrp. The package archive must be named after the package. All packages are made to be expanded to the root. This is the file used by the package configuration menuing system.