Data

Data are what control how the Game Engine acts. As opposed to triggers, data directly changes the game objects so that they behave differently, whereas triggers are actions performed in response to events. In fact, certain core properties of the game engine are only accessible using data (such as controlling the Fog of War colour, as in the image).

Base Objects
Data Objects are seperated into a number of categories. Then each category of data has a number of base objects. When creating your own data object, you need choose which base object the new object will be based on (it is said to inherit from the base object).

As an example, let's take abilities. There is a base object called CAbil which is the base object for all abities. Several other base objects inhert from this CAbil object (a base object inheriting from another base object) such as the CAbilHarvest which represents a harvesting ability (minerals, vespene gas, etc.).

In the data editor, you can tell whether an object is a base object because its name is written in grey in the browser.

Fields
Once you have created your own object and based it on the correct base object, you need to customize and set values for its fields. The different fields for an object are listed on the right side, in the field viewer (if you click on the buttons at the top, you can customize the view to match your preferences). Different fields take different types of values (strings, integers, arrays, etc.) and, by experience, you will learn what each field does. Also, certain fields have been documented in the editor and you can see what these do by hovering your cursor on their name.

Default Objects
Default objects are the built-in objects that come with the game. You can tell whether an object is a default object because its name is written in blue in the browser. Objects which were inserted because of a dependency are listed in orange while objects you create are listed in green.

When you modify the value of a default object, you might be tempted to think that the game actually created a copy of the object (because the browser will list two objects). In reality, you are modifying the default object but it is still listed so that you can easily revert back to the default. So if, for example, you change the movement speed of marines, there aren't two types of marines but rather all existing marines will now use the new version of marines.