Yellow Lines

I think I must have a weird sense of humour. I was in the bank today and they have an escalator, at the top of the escalator there is a notice on the wall saying stay clear of the yellow lines. What is so strange about that, well on the floor under the notice is an area marked out with diagonal yellow and black lines.No way of avoiding the yellow lines if you want to use the escalator. I do wish I could have taken a photo of it but they couldn't give me permission.