classes

Based on http://www.software-lab.de/ref.html#dbase

Database

+Entity^?: superclass of all database/persistent classes, see http://www.software-lab.de/ref.html#dbase

Primitive types like

+Symbol^?: Symbolic data

+String^?: Strings (just a general case of symbols)

+Number^?: Integers and fixed-point numbers

+Date^?: Calendar date values, represented by a number

+Time^?: Time-of-the-day values, represented by a number

+Blob: "Binary large objects" stored in separate files

Object-to-object relations

+Link^?: A reference to some other entity

+Hook^?: A reference to an entity holding object-local index trees

+Joint^?: A bi-directional reference to some other entity

Container prefix classes like

+List^?: A list of any of the other primitive or object relation types

+Bag^?: A list containing a mixture of any of the other types

Index prefix classes

+Ref^?: An index with other primitives or entities as key

+Key^?: A unique index with other primitives or entities as key

+Idx^?: A full-text index, typically for strings

+Sn^?: Tolerant index, using the Soundex-Algorithm

Booleans

+Bool: T or NIL

And a catch-all class

+Any^?