The feature class is a storage location for coordinates and attributes of a feature.
Feature classes encountered in this manual are of the geometry type point, line or polygon. They are analogous to a shapefile or geometry layer of a coverage. When GPS data is checked back into the geodatabase and displayed in ArcMap, each feature class becomes its own layer.
In ArcCatalog, right-click on a feature dataset and choose Properties to view the following details. Explore the Fields tab of the Properties window of a feature class for light poles
The Field Name is the column name in the attribute table. Upon creation of a new feature class, the table is already populated with an ObjectID field and a Shape field. The ObjectID field contains the unique ID number for each feature in the feature class. The SHAPE field defines the type of shape is stored in the feature class (point, line or polygon). The next attribute field, Height_Feet will store the height of the light pole as entered during data collection.
The Data Type of this attribute as shown in the next column is Short Integer (a whole number between –32,767 and 32,767). Refer to the table following these figures for a description of each Data Type. Each light pole located by GPS, digitized or created during an editing session will be recorded as a separate row (record) in the attribute table.
The Field Properties can be viewed for each field at the bottom of the window.
An alias, unlike the field name, does not have to adhere to the limitations of the database, so they can contain special characters such as spaces. By specifying an alias, you can use a more "user friendly" description of the content of the field than their actual field name.
If Allow NULL values is Yes, the user is not required to provide an attribute value for this attribute while collecting the feature.
Default values are entered in the attribute field automatically.
Domains are discussed later in this section.