Fix: files contain columns that are not part of GTFS

Code: unknown_column (MobilityData validator)

What this means

A file in your feed has a column header that is not a field in the GTFS spec.

Apps ignore columns they do not recognise, so these do no harm on their own. The

validator surfaces them because an unknown column is sometimes a misspelled real

one, and that case does cause harm.

Why it matters

Two things hide behind an unknown column. The harmless kind is a vendor extra:

an internal field the export carries that no app reads. The harmful kind is a

typo in a standard field name, like stop_lat written stop_latt or

wheelchair_boarding written wheelchair_boardng. When a real field is

misspelled, every app treats it as missing, so the data you entered silently

does nothing. The check is worth a look precisely because it catches that.

How to fix it

Look at each flagged column name:

• A misspelled GTFS field: correct the spelling so apps read the data again.

Compare against the field names in the GTFS reference; the typo is usually one

or two letters off a real field.

• A genuine vendor extra: it is safe to leave, but removing it keeps the feed

clean and the next reviewer from wondering. Many tools have a setting to export

only standard fields.

How long it usually takes

A quick look at the flagged files. Correcting a typo is a one-line change;

deciding a column is a harmless extra takes only a glance.