C Structs

Hi fags.

I need to know how portable c structs are for data transmission: are the fields in a fixed position determined by some standard?

Actually there must be something not portable... and that's demonstrated by tinyos documentation

These structures MUST be external structs (nx_struct), and all of their fields MUST be external types (nx_*), for two reasons. First, external types ensure cross-platform compatibility [1]....