The file is in ASCII format and contains 245,195 records of 110 characters long (including CR/LF). The records are built according to the proposed format, given in the IMMA document, updated 20 February 2004 (www.cdc.noaa.gov/coads/e-doc/imma/imma.pdf). The idea behind this format is that the user can easily start with the data, without having to concern about unit conversions.

All data ahs been expressed in present day SI-units (e.g. UTC, Celsius, nautical miles, degrees, m/s and hPa). In the laboring process of keying the data from different sources, duplicate records may have been keyed when more than one source was available from the same voyage. Usually these records are not exact copies, but are more or less complementary to each other. The identification of the duplicates is handled in the ShipLogbookID file (ShipLogbookIid.txt). If the user wants to avoid duplicates, he/she has to ignore those ID’s that have the Duplicate-field in the ShipLogbookID file set to other values than 0.

In the following table the record in the file CLIWOC15.txt is explained.
 
Variable Start End Format Description
YR 1 4 A4 Year (UTC)
MO 5 6 A2 Month (UTC)
DY 7 8 A2 Day (UTC)
HR 9 12 A4 Hour (UTC)
LAT 13 17 A5 Latitude in hundredths of a degree; North of the equator is positive, South of the equator is negative
LON 18 23 A6 Longitude in hundredths of a degree; convention: 0-359.99, East of Greenwich
IM 24 25 A2 IMMA version; 0 = this prototype version
ATTC 26 26 A1 Attachment Count; in this version there is no attachment, so the count is 0
TI 27 27 A1 Time indicator; only 0 (= nearest whole hour)
LI 28 28 A1 Latitude/longitude indicator; all 6 (= other)
DS 29 29 A1 Not in use
VS 30 30 A1 Not in use
NID 31 32 A2 Not in use
II 33 34 A2 ID indicator; all 10 (= composite information from early ship data).
ID 35 43 A9 Identification; In this release a number is given that identifies the ship and the ships' logbook and the possibility that the current record is a duplicate.
With this number you can look up this information in the file: ShipLogbookId.txt
C1 44 45 A2 Country code; gives the nationality of the ship that made the observation:
ES = Spain
FR = France
NL = The Netherlands
UK = United Kingdom
SE = Sweden
US = USA
DE = Germany, in this case especially it is restricted to Hamburg
DK = Denmark
DI 46 46 A1 Not in use
D 47 49 A3 Wind direction (from which the wind is blowing) in whole degrees from:
1-360; 361 = calm, 362 = variable.
WI 50 50 A1 Wind speed indicator; all reported wind forces are more or less given in Beaufort classes (WI = 5);
W 51 53 A3

Wind speed; given in tenths of a meter per second. From the descriptive terms of wind force given in the observations, a first division into “Beaufort” classes resulted in the m/s given here. Most of the values are the midpoints of each Beaufort class, cf. WMO-1100. In those cases that more information was available, other values may have been used.

Bft 0: 0-0.2 m/s
Bft 1: 0.3-1.5 m/s
Bft 2: 1.6-3.3 m/s
Bft 3: 3.4-5.4 m/s
Bft 4: 5.5-7.9 m/s
Bft 5: 8.0-10.7 m/s
Bft 6: 10.8-13.8 m/s
Bft 7: 13.9-17.1 m/s
Bft 8 17.2-20.7 m/s
Bft 9: 20.8-24.4 m/s
Bft 10: 24.5-28.4 m/s
Bft 11: 28.5-32.6 m/s
Bft 12: >32.6 m/s

VI 54 54 A1 Not in use
VV 55 56 A2 Not in use
WW 57 58 A2 Not in use
W1 59 59 A1 Not in use
SLP 60 64 A5 Sea level pressure in tenths of hPa. Still under study; No temperature correction was applied and for this moment the following factors have been used for the conversion to hPa:
2.54 cm in an inch
13.596 specific gravity of mercury
980.65 cm/s gravity at 45° latitude
A 65 65 A1 Not in use
PPP 66 68 A3 Not in use
IT 69 69 A1 Indicator for air temperatures, originating from:
3 = mixed precision Celsius
7 = mixed precision Fahrenheit
9 = mixed precision Réaumur
AT 70 73 A4 Air temperature in tenths of a degree Celsius
WBTI 74 74 A1 Not in use
WBT 75 78 A4 Not in use
DPTI 79 79 A1 Not in use
DPT 80 83 A4 Not in use
SI 84 85 A2 Method by which SST was taken; 10 = implied bucket
SST 86 89 A4 Sea surface temperature in tenths of a degree Celsius
N 90 90 A1 Not in use
NH 91 91 A1 Not in use
CL 92 92 A1 Not in use
HI 93 93 A1 Not in use
H 94 94 A1 Not in use
CM 95 95 A1 Not in use
CH 96 96 A1 Not in use
WD 97 98 A2 Not in use
WP 99 100 A2 Not in use
WH 101 102 A2 Not in use
SD 103 104 A2 Not in use
SP 105 106 A2 Not in use
SH 107 108 A2 Not in use