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WMO File Name Recommended Practice Description Documentation

This is a newly developed recommended practice for the exchange of information between Centers over the GTS when they are using FTP to PUSH files to the next center. The recommendation will be published in the November 3, 2003 update to the WMO Manual 386 Attachment 15. The Washington RTH will use this practice for delivery of files containing WMO bulletins. See file ingest documentation for a discussion on accumulating bulletins in files and the structure of the file content using product separators. The file content "flag field" for forming the content of a file of bulletins is applied in the building of all AHL product files in the Gateway.

The following information was extracted from the Cairns, Australia WMO WWW CBS - Ext (02) [4 to 12 December 2002] meeting documents that were recommended for approval as ammendments to Manual 386 Attachment II-15.

FILE NAME STRUCTURE

The file naming convention

The following file naming convention should be implemented with a transition period not exceeding 2007. The file name format is a predetermined combination of fields, delimited by the _ (underscore) character except for the last 2 fields, which are delimited by the . (period) character. each field can be of variable length, except for the Date/Time stamp field which is predetermined.

The order of the fields is mandatory and the file name fields are as follows:

pflag_productidentifier_oflag_originator_yyyyMMddhhmmss[_freeformat].type[.compression]

where the mandatory fields are:

pflag = is a character or combination of characters indicating how to decode the product identifier field. At this time, the pflag field has only the following acceptable values:

Table 4.1 Accepted pflag values

pflag Meaning
T The product identifier field will be decoded as a standard
T1T2A1A2ii data designator (The WMO standard data designators
are given in Attachment II-5)
A The product identifier field will be decoded as a standard
Abbreviated Heading, including BBB as appropriate, space
characters being discarded. e.g. T1T2A1A2iiCCCCYYGGgg[BBB]
W Planned WMO Product Identifier
Z Originating centre's local product identifier

productidentifier = is a variable length field containing information that describes the nature of the data in the field. The productidentifier field should be decoded according to the pflag.

oflag = is a character or combination of characters indicating how to decode the originator field. At this time, the oflag field has only the following acceptable value:

Table 4.2 Accepted oflag values

oflag Meaning
C The originator field will be decoded as a standard CCCC site id

originator = is a varible length field containing information that states where the file originated from. The orginator field should be decoded according to the oflag.

yyyyMMddhhmmss = is a fixed length date and time stamp field. The interpretation of this field should be in accordance with the standard rules set for specific data description and types. Therefore, it may have various significance such as date of creation of the file, or date of collection of data. If a particular date and time stamp field is not specified, it should be replaced by a '-' (minus) character For example: ----311500-- represents a stamp that specifies only the day (31), hours (15) and minutes (00). If there are no rules for a specific data type, this field should represent the date and time of creation of the file by the originator.

type = is a varible length field that describes the general format type of the fiel. Although this information could be considered somewhat redundant to the productidentifier field, it is kept as such for industry accepted standard compatibility. It should be noted that the delimiter before the type field is a . (period). This is to help parse the file name for fields, since the freeformat field could make use of further __ (underscore) to delimit subfields.

Table 4.3 Accepted type values

type Meaning
met The file is a metadata file pair which describes the content and
format of the corresponding information file with the same name.
tif TIFF file
gif GIF file
png PNG file
ps Postscript file
mpg MPEG file
jpg JPEG file
txt text file
htm HTML file
bin a file containing data encoded in a WMO binary code form such as
GRIB or BUFR
doc a Microsoft Word file
wpd A corel WordPerfect file

And the non mandatory fields are:
freeformat = is a varible length field containing further descriptors as required by a given originator. This field can be further divided in sub-fields. Originating countries should strive to make their freeformat descriptions available to others.

compression = is a field that specifies if the file using industry standard compression techniques.

Table 4.4 Accepted compression values

compression Meaning
Z The file has been compressed using the Unix COMPRESS technique
zip The file has been compressed using the PKWare zip technique
gz The file has been compressed using the Unix gzip technique
bz2 The file has been compressed using the Unix bzip2 technique

Maximum file name length:
Although no maximum length is specified for the entire file name, the mandatory fields shall not exceed 63 characters (including all delimiters) to allow processing by all international systems.

Character set:
The filenames shall be compossed of any combination of the standard character set (ITU-T Rec.X.4) with the exceptions noted in Table 4.5.

Table 4.5 Symbols for filenames

Symbol Allowed Meaning
_ yes The underscore symbol is used as a delimiter symbol. To be
used only as a delimiter of fields. The underscore is also
accepted in the freeformat field, but not in other fields.
. yes The period symbol is used as a delimiter symbol. To be used
only before the type and compression fields.
/ no Forward stroke often has special meaning for the full path
specification for a filename in some operating systems
\ no Backward stroke often has special meaning for the full path
specification of a filename in some operating systems
> no Greater than symbol shall not be used since of often represents
special file manipulation in some operating systems
> no Less than symbol shall not be used since it often represents
special file manipulation in some operating system
| no Vertical bar (pipe) symbol shall not be used since it often
represents special file manipulation in some operating systems
? no Question mark symbol shall not be used
' no Single quote shall not be used
" no Double quote shall not be used
* no The star symbol is often used for wildcard specification in
procedures that process filenames
Space no The space symbol shall not be used
, yes The comma symbol can be used in the freeformat field
A-Z a-z
0-9
yes alphanumeric symbols may be used in all fields

The structure of the '.met' file, related to the WMO Metadata standard, is not defined in this guide.

File Name Examples

A possible imagery file (sig weather chart) that would have originated from the USA:

T_PGBE07_C_KWBC_20020610180000_D241_SIG_Weather_250-600_VT_06Z.tif

A possible model output file from France:

A_HPWZ89LFPW131200RRA_C_LFPW_20020913160300.bin

A possible image from Australia:

Z_IDN6000_C_AMMC_200020617000000.gif
Note that: this shows that the date and time stamp is to be interpreted to be 00 hours, 00 minutes and 00 seconds.

A possible compressed TOVS sat4llite data file from the United Kingdom:

Z_LWDA_C_EGRR_20020617000000_LWDA16_0000.bin.Z

A possible image (radar) from Canada:

T_SDCN50_C_CWAO_200204201530--_WKR_ECHOTOP,2-0,100M,AGL,78,N.gif

A possible single-record GRIB file from Canada:

Z_C_CWAO_2002032812----_CMC_reg_TMP_ISBL_500_ps60km_2002032812_P036.bin

A possible multiple record batch file from China:

Z_SM_C_BABJ_20020520101502.txt

 

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