Background

This is another article I wrote ages ago, originally published on Axaptapedia, which no longer exists. I found a copy online thought it was worth sharing as a blog as most of it remains relevant for Dynamics 365 Finance and Operations.

I have not edited the content but I left out a part about creating EDTs in code by an another author who added that later.

Side note: An extended data type is also referred to a an EDT.

Okay, enough of that. Let's start! 

Introduction

Extended data types are very important and if used correctly, very powerful. An extended data type is a user-defined definition of a primitive data type. The following primitive data types can be extended: boolean, integer, real, string, date and container.

Inheritance

Name is a standard string EDT that represents the name of a person, company or object. If a property on Name is changed, all EDT's that inherit from it will automatically reflect the changed value. For example if the standard length is not long enough, it can be increased and all child EDT's will automatically be increased along with it. All database fields, forms and reports where the EDT is used, will also reflect the changed property.

Properties

Some of the properties that can be modified are StringSize, Alignment, DisplayLength, Label and HelpText.

Number sequences

When creating a number sequence, an extended data type is required to associate the number sequence with.

Advantages

1. Consistency in data model, forms and reports.

2. Automatic lookups (if table relation property is set).

3. Improve readability in code.