What is the purpose of a these #define within an enum?

Question

I found this code in the linux headers, /usr/include/dirent.h:

enum   
  {    
    DT_UNKNOWN = 0,
# define DT_UNKNOWN DT_UNKNOWN
    DT_FIFO = 1,
# define D         


        

Answer 1

My guess is that some other code can then check if one of (or more of) these enum values have been defined using #ifdef.