'flip' = illegal name?

I had some trouble this morning using 'flip' as a variable name. My php set


When I tried to print this value in my template like


It acted as though it were blank. When I changed $item->line->flip to $item->line->flip1 and updated my template to use flip1, it worked. Is 'flip' a reserved word? I could not find any mention in the manual.

Thanks for reading.

I think this may be my fault for naming a variable and function the same thing... which I really feel PHP should complain about but apparently it doesn't.

OK