IEEE C37.232-2011 pdf free download.IEEE Standard for Common Format for Naming Time Sequence Data Files (COMNAME).
Meaningful filenames provide software developers with the ability to write programs that can quickly manage and process large numbers of files. The hardware benefits as well from the reduced number of disk access operations. The alternative to meaningful filenames is to build and maintain a specialized database. However, specialized databases are very costly to create and maintain, and they use extremely large memory structures. Accordingly, the recommended filename information is specified in comma-delimited format where commas are used to separate the information into multiple fields. Thus, spreadsheet-like tables can be made from directory listings of filenames. Such tables provide users with an easy way to perform sort and query operations based on any one of the fields in the filename, in effect providing the same look and feel as any other specialized database application. 1.4 Need for this standard The standard naming convention has been gaining popularity and has so far been used by a nontrivial number of utilities, independent system operators, manufacturers, electric reliability commissions, and third-party developers. The North American Electric Reliability Council (NERC) and the Northeast Power Coordinating Council (NPCC) have recommended the use of a common file naming convention. 2. Definitions For the purposes of this document, the following terms and definitions apply. The IEEE Standards Dictionary: Glossary of Terms & Definitions [B5] should be consulted for terms not defined in this clause. 1, 3.2 Naming conventions for TSD files Several naming conventions are in use today. These formats can be organized in three classes: associated, coded, and sequenced. Associated means the filename extension defines the type of data storage format. For example, the extensions “.HDR,” “.CFG,” “.DAT,” and “.INF” are used to indicate that the file contents are compatible with IEEE Std C37.111™-1999 [B6]. The nonextension part of an associated filename is totally up to the user. Coded means the filename contains some information about the event. In this case, the storage format is usually manufacturer specific. For example, certain files that are generated from digital fault recorders have the event date and time (up to 12/31/2079-23:59:59.99) and the recorder number (up to 255) coded in the filename. The recorder number is coded in the first two characters of the name, and the date and time are coded in the last nine characters of the filename. The resulting filename is not friendly, and reading it requires special decoding software. For example, “G30BQ1EF.063” is the filename assigned by device number 163 on 09/18/1991 at 14:15:00.630. A detailed example of a similar scheme used to compress over 70 characters of key event information into the old 8.3 filename format is presented in Annex A. The sequenced filenames format is an incremental approach to naming files. This method is valid because the resulting filenames are unique. The sequence may appear in the name or in the extension portion of the filename. The total number of attainable filenames is limited to the maximum value of the numerical sequence. When multiple devices are used, then the device numbers are also coded in the filename. For example, some filenames have the location name (up to four characters), the event number (up to four characters, 9999 filenames before overwrite), and the channel group number (up to three characters).
Half-byte packing is a procedure used to mask out repeated patterns in character bits. For example, the characters 7 and 14 represented by the bit patterns 0000-0111 and 0000-1110 can be packed in one byte by masking out the upper 4 bits from both characters. The resulting byte will have the bit pattern 0111-1110. Character bits are not always repetitive, and bit manipulation is not natural for byte-based machines. Huffman coding is a simple method where the probability or relative frequency of the occurrence of each symbol in a stream of information is used to compress the information. Symbols with highest probability are assigned to codes with shortest length. For example, if the term filename appears frequently, then it can be assigned the code “-,” which saves seven characters per appearance. Dictionary and adaptive dictionary coding are compression methods that are similar to Huffman coding. Instead of assigning short codes to frequent terms or phrases, terms are replaced by pointers to their location in a dictionary or a list of unique entries. Repeated terms are reduced to repeated pointers. In the adaptive method, repeated terms are replaced with pointers to their initial place of occurrence. Popular file compression programs use a similar adaptive technique. The preceding methods are designed to compress information using standard characters. However, some characters are not allowed in filenames. The disallowed characters are defined in Clause 2. Accordingly, applying these compression methods could produce non-valid filenames. To eliminate this problem, an alternative code set is used. The set is composed of the characters that are allowed in the filename. The alternative code set is normally called the filename character set.