1. Overview 1.1. Scope Develop a recommended practice for a file format suitable for exchanging power quality related measurement and simulation data in a vendor independent manner. Appropriate definitions and event categories to be developed by other task forces under the IEEE Standards Coordinating Committee 22 （SC22） on Power Quality and the IEEE 1159 Working Group on Power Quality Monitoring. 1.2. Purpose A variety of simulation， measurement and analysis tools for power quality engineers are now available from many vendors. Generally， the data created， measured， and analyzed by these tools are incompatible between vendors. The proposed file format will provide a common ground that all vendors could export to， import from to allow the end user maximum flexibility in choice of tool and vendor. There are two “l(fā)ayers” to this Power Quality Data Interchange Format （PQDIF）： the physical layer and the logical layer. The physical layer describes the physical structure of the file without regard to what will actually be stored in it. It uses tags to identify particular elements of the file. This is similar in concept to TIFF （Tagged Image File Format）， used for storing images. The logical layer uses the structure defined by the physical layer; it specifies specific tags to use when building up elements in the file.