The kind is meant to store the general purpose data in the database and presenting / editing it via user interface.
In general, if you need to create a composite data type with items stored in the database (not transient) which is an independent entity (not integral part of another type) you should create directory data type unless there are no strong reason for this type to be a Document.
The individual objects (instances) of types belonging to this kind are referred to as “records” in context of Codejig ERP.
Directory data types allow system instances.
Each directory data type includes identifier, serial number, metainfo and relative order as shared fields. See predefined shared fields for more info.