A domain is a standalone dictionary object that defines technical and semantic attributes of elementary data types.
Data elements can be defined with reference to a domain and inherit its attributes. Domains can only be used in data elements.
Domains are located in a different namespace from data types. A domain can have the exact same name as a data type and, more particularly, a data element.
Redundant domains within an application component or a package should be avoided. Domains that only
have technical attributes must be created as reusable domains in central basis packages. One example is the domain CHAR255.
The fixed values of a domain can be used as special literals in
CDS views as well as the full domain being used in data elements.