The following explains the field codes in the 'fixed event'
data type for the CSIRO flask network data contained in the
WDCGG archives. Specifically, the data flag (F), sample
collection method (c), and analytical instrument (ii) codes
for the CSIRO flask event data (for the species CH4, CO2, 
CO, H2 and N2O) are explained.
For more specific information on sampling and measurement 
techniques, please see the "Stations" page, select a CSIRO
station, then click on the station name to get to the
"Information on the Measurement Site" page. From here 
select a species from the parameter line to display the
"Information on Measurement Programme" page for that species.
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Data flags (F) for CH4, CO2, CO, H2 and N2O
fff - flags: "..." indicates no flags, sample retained.

First flag column:
  Any entry other than "." in the first flag column indicates
  the sample is not representative of the time and place of
  sampling:
    A = no sample taken
    B = sample lost before analysis
    C = identified sampling error
    D = suspected sampling problem (eg. 2 or more
         species give anomalous values)
    E = mixed samples (time/place not unique)
    N = unacceptable analysis
    * = no analysis data available
    H = species-specific manually applied rejection flag
    I = species-specific sample collection problem
    J = irretrievable sample storage effect
    . = not subject to any of the above flags

Second flag column:
  Any entry other than "." in the second flag column indicates
  the sample is non-baseline, rejected only on grounds of
  being an outlier or is excluded from this data set because
  of a non-standard sampling technique:
    F = non-baseline meteorological conditions
    G = marginal-baseline meteorological conditions
    K = species-specific non-baseline
         meteorological conditions
    L = species-specific marginal-baseline
         meteorological conditions
    M = 3 sigma filter rejected
    O = non-standard sampling technique
    . = not subject to any of the above flags

Third flag column:
  The third flag column is currently not used.


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Sample collection method code (c)
  c - sample collection method code for the retained data:
    A = GASLAB flask pump unit (FPU) with anhydrous
         Mg(ClO4)2 drying,
    D = metal bellows pump with anhydrous Mg(ClO4)2 drying,
    C = manual aircraft sampling unit with anhydrous
         Mg(ClO4)2 drying,
    H = automated aircraft sampling unit with anhydrous
         Mg(ClO4)2 drying,
    6 = method not directly recorded


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Analytical instrument code (ii)
  ii - analytical instrument code

CO2: C3 - Samples were analysed by gas chromatography with
     flame ionisation detection after methanization of CO2 to CH4.
     One Carle gas chromatograph, labelled "Carle-3" (C3) was used
     over the length of the record. Data are reported here in the
     WMO CO2 mole fraction calibration scale.

CH4: C1, C2 or C3 - Samples were analysed by gas
     chromatography with flame ionisation detection (FID). Three
     individual but similarly configured Carle gas chromatographs
     were used over the length of the record. They are labelled
     "Carle-1" (C1), "Carle-2" (C2) and "Carle-3" (C3).

CO and H2: R1 - Samples were analysed by gas chromatography
     with a mercuric oxide reduction gas detector. CO reduces HgO
     to Hg vapour which is detected by UV absorption. Similarly, H2
     reduces HgO to Hg vapour which is detected by UV absorption.
     One Trace Analytical gas chromatograph, labelled "RGA3-1" (R1)
     was used over the length of the record.

N2O: S1 - Samples were analysed by gas chromatography with
     electron capture detection. One Shimadzu gas chromatograph,
     labelled "Shimadzu-1" (S1) was used over the length of the
     record.