I think the meaning has changed somewhat because the chart isn't really an focus of Joe public anymore right? Who cares if something is number one? We had TOTP and the pepsi chart show on the radio and it was a big deal but what is there now?
I just class it as they want mainstream popular tunes of the past few years. I always ask for particular song requests as genres such as chart are often wildly misinterpreted so chart could be Stormzy, Walk the moon or as someone mentioned, Yazz :D