How to set or change "Loading" text?

Sometimes, when loading a page, I see a “Loading” label appear.

I attach a screenshot of this…

How can I set or change this “Loading” text?

Thanks to the room,
I learnt that (at least for the code that I’ve inherited)
the source of the Loading message is Iron Router…

I’m able to tweak the Loading message via the loadingTemplate attribute of Iron Router, cf