Everything that the product processes.
Input: any data that is processed by the product.
Output: any data that results from processing by the product.
Preset: any data that is supplied as part of the product, or otherwise built into it, such as prefabricated databases, default values, etc.
Persistent: any data that is stored internally and expected to persist over multiple operations. This includes modes or states of the product, such as options settings, view modes, contents of documents, etc.
Sequences/Combinations: any ordering or permutation of data, e.g. word order, sorted vs. unsorted data, order of tests.
Cardinality: Numbers of objects or fields may vary (e.g. zero, one, many, max, open limit). Some may have to be unique (e.g. database keys).
Big/Little: variations in the size and aggregation of data.
Noise: any data or state that is invalid, corrupted, or produced in an uncontrolled or incorrect fashion.
Lifecycle: transformations over the lifetime of a data entity as it is created, accessed, modified, and deleted.