Script Debugger can save compiled script files in three formats. You can choose a format either from the File > Script Format hierarchical menu or from the Save dialog.

• Compiled Script (Data Fork). A file with the compiled bytecode in the data fork. This is the default format created by the current version of Apple’s Script Editor. It is backwards compatible to all versions of Mac OS X and to very late versions of AppleScript in Mac OS 9.
• Compiled Script (Bundle). A bundle (package) with the bytecode as a data fork compiled script file inside the bundle. This format was introduced in Panther (Mac OS X 10.3) and is not backwards compatible to earlier systems. It has the advantage that you can store ancillary files inside the bundle, but be warned that some applications do not understand this format.
• Compiled Script (Resource Fork). A file with the compiled bytecode in the resource fork. This is the oldest format and is compatible with all Macintosh systems and all versions of AppleScript.

Keeping the bytecode in the resource fork is, however, also the riskiest format. You can accidentally strip away a compiled script’s resource fork. You might, for example, save the compiled script file on a non-HFS filing system (true Unix, or Windows), or send it through email without compressing it, or open it with some badly behaved script editor application.

Warning: A compiled script saved in debug mode will not run normally in other environments (and will not even open in Apple’s Script Editor). Unless that’s what you intend, be sure to save the script in normal mode when you’re finished debugging it.