StartSession starts/initialises a new DB session.

Creating implies Modifying (which in turn implies Reading).

Modifying implies Reading.

Valid activities: the "higher level" activities inherit the activity abilities of the activity levels lower down the scale.

sentinal error returned when requested database is not available.

Session keeps track of a database session.

Entry represents the generic entry in the database.

Activity is used to specify the general activity of what will be occurring during the database session.

Deserialiser extracts/converts fields from a SerialisedEntry.

SerialisedEntry is the Entry data represented as an array of strings.