Some TRADAS users prefer to have database fields that are custom and specific to only their agency. The TRADAS product handles this type of need through the optional site custom fields feature. Each traffic site location may also have up to 10 custom site fields. These fields will not show up in the Site Name field on standardized, non-custom reports, but are used for internal purposes. Similar to the naming conventions that are defined in the system, custom site fields have a type, which can be either a number of varying precision or a varchar2 (a character string). Each field can also have a domain, which gives the set of possible values for that custom field. A domain can be a range (e.g., 4-26) or a list of discrete values (e.g., 'A', 'E', 'I', 'O', or 'U').