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GATEWAY
File Standards & Content Structures

Directory/File Name Standards

The Gateway server directory tree and file naming conventions as implemented at the NWS on the Telecommunication Operations Center's Servers are outlined here as guidance. You will find on our servers one of two major file structures. The two implementations were developed over time through various U.S. committees such as through the OFCM working groups or by the TOC. The first one is called the TOC Directory and File Name Standard and is used for all files of products and other data stored on the TOC Gateway File Servers. The second file structure and directory naming procedure was developed for the data and products that have been parsed into individual items for selective HTTP and/or FTP retrieval. These files were initially for internal use in web display processes. However, to enhance our support to the public, these files were opened to anonymous FTP access. The directory and file name practice is called the English Descriptive Format and documentation has been published. These files of data and products do not use the "Flag Field Separator" discussed below. Please review the Help Guide for details on FTP downloading procedures for retrieving individually parsed products and observations.

The WMO CBS-Ext(02) meeting held 4-12 December 2002 has submitted a new File Name Recommended Practice for approval. This recommendation is planned for use in "pushing" files among GTS centers.

File Content Structure

There is an information block separator field called a Flag Field Separator [written in ACSII character code] contained in the file when the file contains WMO bulletins (or AWIPS Identifiers) to help in reading and processing multiple bulletins in the file. File contents vary depending on intended use or file generation time. When the data and products are contained in WMO bulletin form they generally follow one of the two flag field practices listed below to separate bulletins within a file. There is a special option for delivery of some files to specific customers. Some files contain only one bulletin such as a fascimile chart or an NCEP GRIB or BUFR product. Some files may contain model products not in WMO bulletin format (no WMO abbreviated heading) and do not have flag field separator blocks. However, the product content will be in a standard WMO exchange code format. Please review the Help Guide for details on FTP downloading procedures for retrieving files of WMO bulletins of products and observations. Also, remember that the files written in the "English Descriptive Format" do not have the "Flag Field Separator" blocks in the files.

  • Bulletin "Flag Field Separator" block - OPTION 1 (old)
    1 - 4
    5 - 7
    8 - 13
    14 - 17
    18
    marker string (####)
    block length [018 fixed value]
    total length of bulletin in bytes [octets] (not including the flag field block)
    marker string (####)
    line Feed (ASCII "0A")

  • Bulletin "Flag Field Separator" block - OPTION 1a (special purpose)
    1 to 4
    5 to 7
    8 to 18
    19 to nnn-5
    nnn-4 to nnn-1
    nnn
    marker string (####)
    block length (nnn) - value always greater than 018
    total length of bulletin in bytes [octets] (not including the flag field block)
    reserved for future use
    marker string (####)
    line Feed (ASCII "0A")

  • Bulletin "Flag Field Separator" block - OPTION 2 (new)
    1 - 4
    5 - 14
    15 - 18
    19
    marker string (****)
    total length of bulletin in bytes [octets] (not including the flag field block)
    marker string (****)
    line Feed (ASCII "0A")

NOTE: All numeric values in the flag field separator group are right-justified with leading zeros. The position count annotation is FROM first character placement value TO last character placement value within the flag field starting with one (1) as the first annotated position within the block.

The option 1a implementation was established to permit product size definitions beyond the limits of option 1.

 

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     Page last Modified: 15 February, 2012 1:50 PM