JAD files: JAD (file format - Wikipedia, the free encyclopedia
The JAD file is used as an "application descriptor" file, which is a standard format for downloading J2ME applications over-the-air, using a web browser. It's a text file full of name-value pairs, several of which are crucial (the "size" parameter must exactly match the size of the referenced file being downloaded).
COD files: Blackberry COD file format « Reverse & Ð¤Ð¾ÑÑÐ°Ð¶
A COD file is a RIM-style code module. The BlackBerry rapc compiler produces a COD file from all the class files in its project. It then produces a JAD file to support the COD file being downloaded to a BlackBerry through a BlackBerry Web browser. Normally this would be all you needed. However, a lot of BlackBerry applications require their COD files to be signed by the RIM signing server - this entails the addition of a digital signature to the COD file so that the application is permitted to access RIM protected APIs on a real device. This necessarily changes the size of the COD file, making it noticeably different from the aforementioned "crucial" size value in the JAD file. RIM has created a utility application to adjust the rapc-built JAD file post-signing.