Where 'frozen' versions exist, they are suffixed .ICE, .ICE2 etc for successive ice ages. Each trial centre or group is given an arbitrary serial number, e.g. 123. Some centres or groups may have more than one serial number, e.g. because data were received via different routes. Where a trial is divided into strata the stratum numbers are appended, e.g. 84J1, 84J2. The year mnemonics are subject to change as new information is received.
Parameters can be names, letters, numbers etc depending on circumstances.
CTSU diktats about the interpretation of death causes etc vary continually.