Index of ESRI Shapefiles (.SHP files) that stores index and offset information from the main Shapefile; allows for direct access to records in the main file; consists of a 100-byte header followed by 8-byte, fixed-length records that define the SHP files referenced by the index file; often saved along with a corresponding dBASE (.DBF) database file.

Encrypted file used to "flash" the firmware of a Motorola cell phone, such as as a Razr or Rokr; often used for customizing or "modding" the interface of Motorola cell phones.

To flash the memory of a cell phone, you must connect the phone to a PC via USB and run a program like PST or RSD, which can open the flash superfile.

SHX files are based on the .HS flex file format.