External Collection of value keys, status codes etc.

STRING will avoid to define possible values for elements in enumerations inside the schema files as this leads to validation violations when new values are added within the same version. We decided to collect these values in a central place on the project server alongside the schema definitions where they will be updated as needed.

The rules regarding these definitions are:

• You are supposed to use only values defined by STRING but you are not enforced to do so.
• You should detect unknown values and fail gracefully. Depending on the environment this could mean to just ignore it or to produce a meaningfull error message.
• If you need a new value (that is: you use a value in a communication between two partners already and think it should go into the common definition) please feel free to propose it to the STRING board (TODO: add link to documentation about this process).

Messages and Enums are kept on a public webserver and may be included into automatic build processes.

Categories of STRING codes and messages

Value Keys for Configuration Response

Key	Description
max_travellers	maximum number of travellers in a transaction / booking
max_services	maximum number of services in a transaction / booking
[...]	[...]

Credit Card Codes

Key	Description
MA	Mastercard (we use only one code of the different ones in circulation)
VI	Visa
AX	American Express
DI	Diner's Club
[...]	[...]