"Monolingual text" is a container datatype that associates a text value with a specific language code. The datatype does require a language code (i.e. a value annotation without a language code is not accepted).
The database is currently locked to new entries and other modifications, probably for routine database maintenance, after which it will be back to normal.
The system administrator who locked it offered this explanation: The wiki is under maintenance. Das Wiki wird derzeit gewartet.
