Enumerations
Enumerations are concepts that include a list of possible values.
You write the definition of an enumerated domain by using the following syntax:
<a concept> can be one of: <value>, <value>, <value>, <value>.
The following example creates a category enumeration with a list of values.
a category can be one of: Economy, Economy Plus, Business, First.
The following example shows a ticket entity that has a category attribute that is of type enumeration.
a ticket has a category.