Motivation

There are two distinct situations in which it is necessary to maintain, independently of the data itself, bit masks associated with every SNO event:-

Public Data Sets

There has to be collaboration-wide agreement on the categorisation of all the raw data. This will be done by applying standard tests within the SNOMAN framework. These tests will develop over time so it will not be possible to apply them as the raw data is first written to tape. Some of the tests will be compute intensive so it will not be practical to apply the tests on the fly each time the data is processed.

Private Data Sets

Individuals need a way to collect lists of events that pass selection criteria of their own devising. A mechanism is need so that these lists can be created and exchanged without requiring exchange of the raw data they apply to. See section 10.3.4.