# The SEF File Format¶

SEF files look like this:

SEF	0.0.1
ID	DWR_Zarate
Name	Zárate
Lat	-34.0958
Lon	-59.0242
Alt	NA
Source	NA
Repo	NA
Var	msl pressure
Units	hPa
Meta	PTC=T,PGC=?
Year	Month	Day	HHMM	TimeF	Value	Meta
1902	12	22	700	0	1005.91
1902	12	23	700	0	1009.78
1902	12	24	700	0	1000.18
1902	12	25	700	0	1015.11
1902	12	26	700	0	1009.65	PTC=T,PGC=?
1902	12	27	700	0	1009.78	PTC=T,PGC=?
1902	12	28	700	0	1014.05
1902	12	29	700	0	1016.18	PTC=T,PGC=?


One SEF file contains observations of one variable from one station. It is a text file encoded as UTF8. It is a tab-separated values file and should have a .tsv extension. This means it can be easily viewed and edited in any text editor or spreadsheet program (though care should be taken to preserve the tab structure and text encoding).

## Data table¶

Lines 12 and onward in the file are a table of observations. Line 12 is a header, lines 13 and on are observations. Missing values can be given as NA or left blank. The table must contain these columns in this order:

Year: Year in which the observation was made (UTC). An integer.

Month: Month in which the observation was made (UTC). An integer (1-12).

Day: Day of month in which the observation was made (UTC). An integer (1-31).

HHMM: Time of day at which the observation was made (UTC). A 4-digit integer where the first 2 digits give the hour of the observation, and the last two digits give the minute. If the hour of observation is less than 10, the first digit may be omitted.

TimeF: Time period of observation (instantanious, integrated over previous 24 hours, …). Integer code. There is a table of meaningful codes.

Value: The observation value.

Meta: Anything else. Comma-separated string of metadata entries. Each entry may be any string (except no tabs, commas, or carriage returns). There is a standard list of meaningful entries, but other entries can be added as necessary. Metadata specified here only applies to this observation, and overrides any file-wide specification.