I do not use SDCC, but since "data" is a language-extending keyword for Keil C51, I went ahead looked at the SDCC on-line documentation and see that it too uses "data" as a keyword like Michael suggested. I did this partly for my own curiosity and partly to see just how fast one could have found this out (< 90 seconds, by the way).

So there's the problem -- improper use of the "data" keyword.