One of the advantages of storing your data in a geodatabase is that you can define rules about how the data can be edited. In this exercise you will see how to define these rules by creating a new attribute domain for lateral diameters. Later you will see how to create subtypes for the Laterals feature class; and associate the new domain, existing domains, and default values with fields for each subtype.

Attribute domains are rules that describe the legal values of a field type. Multiple feature classes and tables can share attribute domains stored in the database. However, not all the objects in a feature class or table need to share the same attribute domains.

For example, in a water network, suppose that only hydrant water laterals can have a pressure between 40 and 100 psi, while service water laterals can have a pressure between 50 and 75 psi. You would use an attribute domain to enforce this restriction. To implement this kind of validation rule, you do not have to create separate feature classes for hydrant and service water laterals, but you would want to distinguish these types of water laterals from each other to establish a separate set of domains and default values. You can do this using subtypes.

You will use ArcCatalog to create a new coded value attribute domain. This new domain will describe a set of valid pipe diameters for your new Laterals feature class.

To add a domain, right-click the geodatabase and click Properties. Click the Domains tab, then click the first empty field under Domain Name and type the name of the new domain. In the Description field, type the domain’s description.

Next, specify the type of field this domain can be associated with, the type of domain it is—range or coded value, the split and merge policies, and the valid values for the domain.

A range domain describes a valid range of numeric values, and a coded value domain describes a set of valid values. In this example you see how to create a new coded value domain.

All domains also have split and merge policies. When a feature is split or merged, ArcGIS looks to these policies to determine the values of the resulting feature or features for a particular attribute.

The next step is to type the valid values, or codes, for the coded value domain, and for each code to provide a user-friendly description. ArcMap uses the description, not the code, for values of fields that have coded value domains associated with them.