In order to select data taken only by commercial ships, excluding
specialist ship data sources such as research vessels, a selection criteria has been established.

Data selection rules are shown in following table. Reports require a day of the month present and to be valid (e.g. 30 Feb not used), but data with a missing hour are included for certain `dck` between 1850 and 1872.  

Each action in the following table corresponds to an `ifelse` statement in [split_by_type.R](https://git.noc.ac.uk/brecinosrivas/icoads-r-hostace/-/blob/master/rscripts/split_by_type.R)
________________
Rule | Action
:----- |:------------
`pt` missing & <br>`dck` = 128, 150, 151, 152, 155, 156, 192, 201, 255, 701, 721, 875, 897, 899 | `pt` = 0 (ship)
`pt` missing & <br>`dck` = 797 | `pt` = 13 (C-MAN)
`pt` missing & <br>`dck` = 896 & <br>`id` contains PLAT or RIG | `pt` = 15 (platform)
`pt` missing & <br>`dck` = 896 & <br> `id` contains SHIP     | `pt` = 0 (ship)
`pt` missing & <br>`dck` = 896, 883 & <br> `id` starts with number   | `pt` = 6 (moored buoy)
`pt` missing & <br> `dck` = 896 & <br> `id` contains 4Y or C7     | `pt` = 2 (OWS)
`irf` = 2 except `dck` = 732 | Use ICOADS `irf` flag but retain `dck` 732 regional exclusions
 `pt` = 7    | Exclude drifters
 `pt` = 6    | Exclude moored buoys
 `pt` = 13    | Exclude C-MAN
 `pt` = 14    | Exclude other coastal or island stations
 `pt` = 16    | Exclude tide gauges
 `pt` = 18    | Exclude profiling floats
 `pt` = 19    | Exclude undulating oceanographic recorders
 `pt` = 20    | Exclude pinnepeds
 `pt` = 21  | Exclude gliders
 `dck` = 795, 995   | Exclude C-MAN
 `dck` = 735, 740, 780, 782    | Exclude research vessels
 `dck` = 793, 794, 993, 994    | Exclude moored buoys
 `id` = PLAT, BUOY, RIGG, BOUY    | Exclude non-ship data
 `id` missing & <br> `dck` 700    | Exclude drifters
 `id` = 5 digits & <br> `dck` = 700 & <br> `sid` = 147 & <br> `pt` = 5  | Exclude buoys
 `id` = 5 digits & <br> `dck` = 892 & <br> `sid` = 29 & <br> `pt` = 5   | Exclude buoys
 `id` contains TEST but /= CONTEST    | Exclude suspect data
  Invalid day   | Exclude data with invalid dates
  Hour missing   | Except for `dck` = 246, 701, 721
** At least one present of  `sst`, `slp`, `at`, `w`, `d`, `ww`, `n`, `wbt`, `dpt`, `vv`, `rh`, `wh`, `nh`, `w1`, `osv` | Exclude reports with no selected variables.

The data is grouped according to the following type of platform:
- SHIP
- DRIFT
- PLAT
- COAST
- MOORED
- SUBMARINE
- RESEARCH
- also REJECT (DY missing or HR missing for data after 1872 or ICOADS IRF reject)