There are two crash file formats, (MobileCrash file and D_EXC file):
When the MobileCrash application is running on the target device, it produces a log file in a case of a panic or crash. The log file is stored in binary format to an MMC card root or to C:\data if no MMC card exists.
D_EXC file is a file which contains crash data. One crash contains two different files: