File Naming Convention

2005-10-17

Description

This document describes the file naming convention used in the ESPO exchange data archives. The naming convention was adopted in 1998 as an extension to the old, DOS-compatible naming convention. The file naming convention uses the ISO 9660 convention which permits name.ext to be 30 characters, and uses the character set:
0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ_
Notice that the alphabetic characters are upper case. The general expression for any file name is:
CCyyyyMMdd[_[hh[mm[ss]]][_c][_Ln][_Vn]].P
The square brackets [ ] enclose optional parameters, and the total length of the file name does not exceed 30 characters. The definitions of the component parameters are:
CC
represents a two-character prefix for the file name (0-9, A-Z). Ideally, this will be a mnemonic code for the measurement, instrument, or subject of the file.
yyyy
represents four digits specifying year (i.e. 1997, 2001, etc.).
MM
represents two digits specifying month number (01-12).
dd
represents two digits specifying day number (01-31).
hh
represents an optional two digits which specify an hour (00-23).
mm
represents an optional two digits which specify minutes (00-59).
ss
represents an optional two digits which specify seconds (00-59).
c
represents an optional identifier for a particular type of file, where c can be one or more characters.
Ln
represents an aircraft launch counter. When the contents of a file pertain to a second or third aircraft launch on the indicated date then use Ln to indicate the launch number (i.e. L2, L3, etc.). If this parameter is omitted from the file name then launch number one is implied.
Vn
represents a volume counter for a multi-volume set of files. It is unlikely that this option will ever be used in the online archives, but its description is included, just in case it becomes useful.
  1. For ASCII data files, the volume number (the n in Vn) must match the volume number (IVOL) in the sixth line of the file header.
  2. The number of digits used in each volume number must be the same (V1, V2, V3, ..., or V01, V02, V03, ..., etc.).
  3. If Vn is omitted from the file name then volume number one of a one-volume file set is implied (the default).
P
represents two or more characters to identify the measurement platform, source, or association of the data (for data files), or image file type (for image files).
Some details to notice are:
  1. Dates and times in file names are always UTC.
  2. In general, the date and time in the file name give the date/time at which the data within the file begin (data files), or date/time at which the image applies (image files).
  3. There can be two, four, or six digits following the first underscore, which represent hh, hhmm, or hhmmss.
  4. If a file name does not include a time but does include other optional parameters then the first of those parameters is separated from the date by two underscores, e.g., CCyyyyMMdd__Ln.P.
  5. File name codes are constructed from the constant parts of the file names and used as a shorthand way to reference a particular type of file. File name codes have one of the following forms (the date/time and Ln and Vn are variable parts of a file name):
    1. CC.P
    2. CC__c.P
  6. For a particular archive account, each file name code must be unique, and therefore each file name will also be unique.
  7. If two or more file codes use the same prefix CC and extension P then all of those codes must also include a c identifier, and each CC__c.P code must be unique.
  8. File catalogs (datatable.* and imagetable.*) are included in the docs directory of each archive account to link file name codes, and therefore file names, with the contents or subject of each type of file.

Examples

Some examples of file name codes, file names, and explanations of the meaning of the file names are given below to illustrate the construction of file codes and file names.
File CodeFile NameExplanation
O3.ER2O319920116.ER2ER-2 O3 file, 16 January 1992 launch
MM.DC8MM19960416.DC8DC-8 MM file, 16 April 1996 launch
CL__5HZ.DC8CL19960416__5HZ.DC8DC-8 5Hz CL file, 16 April 1996 launch
CL__5HZ.DC8CL19960416__5HZ_L2.DC8DC-8 5Hz CL file, for second launch on 16 April 1996
NA.T39NA19960507__L2.T39T-39 NA file, for second launch on 7 May 1996
RS.RAOBRS19920116_12.RAOBRadiosonde soundings from 12Z launches on 16 January 1992
CP.PDFCP20020803_1234.PDFPDF image file depicting data from 12:34Z on 3 August 2002