Someone I know had a BD-issued ticket for EMA-CDG on BD, and a separate AF-issued ticket for CDG-BCN on AF, but on a legal connect.

The BD check-in agent at EMA refuse to through-tag his bag to BCN, on the grounds that the second sector was not on the same ticket. The result was that the client waited 9 hours for a bmibaby flight direct to BCN, and had to pay an excess baggage charge, about both of which he is very unhappy. (Don't ask me why he decided to wait for a WW. It sounds crazy to me. I'd have just lugged my bag at CDG.)

Anyway, his TA's airline liaison office has replied that the agent was correct, it is an IATA ruling, luggage can only be tagged as far as the single ticket indicates, no down or off lining permitted.

Query - is this right?

I know I've had interline transfer bags through-tagged when the sectors have been on different carriers, each of which issued its own ticket. Is that done by carriers as a concession, and is the IATA rule as stated above?