D3 Dictionary Structure

The D3 file structure is made up entirely of files with two parts:

Data section

Describes where the information resides and contains items that, in turn, can contain zero or more attributes. The raw data in each attribute has no definition as to what the data represents. In D3, the definitions are stored in the dictionary section. Each data attribute has a corresponding dictionary entry describing what that data represents and how the data is entered and displayed.

Dictionary section

Describes how the data is to be viewed or manipulated. These entries are dictionary items and refer to data attributes (fields) by their position within the item, for example, first attribute, second attribute, and so on. The meanings are fully described in a dictionary item called attribute-defining item. There may be several attribute-defining items defining the same attribute, offering different views of the same data.

To enter or output data, the attribute must have a dictionary item that defines it or it can use the system default attribute-defining items. The predefined attribute-defining items are a1, a2, a3, and so on. A1 references attribute 1, a2 references attribute 2, and so on.

Since the dictionary section of a file is also a series of items made up of attributes, there are corresponding definitions for them.

These topics are presented:

D3 File System