A lack of understanding doesn't mean data is inconsistent.

For example, in time past one could buy a qualifying paid F fare and then utilize SDC on a ticket of SFO - SNA into SJC - SNA, but since there were (and still are) currently no direct flights AS would reroute through SEA; hence, turning SFO - SNA into SJC - SEA - SNA, and said ticket followed the fare rules and SDC change rules. However, AS updated the SDC change rules and one can no longer exercise a SDC even on a qualifying fare if no direct flights exist between the new desired airports. For example, if you hold SFO - LAX, you can SDC that into SJC - LAX but you cannot SDC into SJC - SNA.🤙🏻🍹