Data Types
The Data Types section covers the AOT objects that define reusable, semantically meaningful types in Dynamics 365 Finance & Operations. Every table field, form control, method parameter, and variable should reference a data type rather than a raw primitive — this ensures consistent labels, validation, formatting, and lookup behaviour across the application.
Extended Data Types (EDTs)
Extended Data Types extend one of the system's primitive data types (string, integer, real, date, etc.) with additional metadata: labels, help text, string sizes, formatting rules, and relations. EDTs support inheritance — a child EDT inherits all properties from its parent and can override any of them.
Base Enumerations
Base Enumerations define a fixed list of named symbolic constants backed by integer values. They are the standard mechanism for representing closed sets of options — statuses, types, categories, modes, and similar classifications. The runtime stores the integer value in the database but presents the label to the user.
Extensions
| Extension Type | Description |
|---|---|
| EDT Extensions | Modify existing EDTs — change string size, add relations, update labels |
| Base Enum Extensions | Add new values to existing base enumerations |
Code Examples
Code Examples — X++ patterns for working with EDTs and enums at runtime.