invalid_language_code: GTFS validation rule Error
A language field does not match a pragmatic BCP 47 pattern (full IANA registry lookup is not enforced).
What the rule checks
A language field does not match a pragmatic BCP 47 pattern (full IANA registry lookup is not enforced).
Severity: error
An error marks data that breaks the GTFS specification. A journey planner or a rider app may refuse the file, or show a wrong version of it. Correct it before publishing the GTFS.
Where it applies
The rule checks the format of a value: it applies to every field of that type, in any GTFS file that has one.
Finding and correcting it
Open the GTFS in GTFS Express. Reading is free, and the validation, by the MobilityData validator and the rules of GTFS Express itself, lists the occurrences of invalid_language_code with the file and rows involved. The correction is made in a draft, by hand or from a brief, with the licence: the corrected GTFS is validated again before it is delivered, and the change can be undone.
In the MobilityData validator
The MobilityData GTFS validator uses the same code, invalid_language_code. Its documentation describes each rule: MobilityData validator rules.