About the information in *.M51

Dear Sir, May I leanr the meaning of the L?xxxx ?
Where could I find the description of M51 in KeilC?
Thank you.

  C:32E1H         SYMBOL        L?0506
  C:32E4H         SYMBOL        L?0507
  C:32EBH         SYMBOL        L?0512
  C:32F8H         SYMBOL        L?0513
  C:32FBH         SYMBOL        L?0514
  C:3303H         SYMBOL        L?0517
  C:3303H         SYMBOL        L?0518
  C:330AH         SYMBOL        L?0521
  C:3332H         SYMBOL        L?0522
  C:3332H         SYMBOL        L?0523
  C:3334H         SYMBOL        L?0524
  C:3335H         SYMBOL        L?0525
  C:333BH         SYMBOL        L?0529
  C:333FH         SYMBOL        L?0530
  C:3349H         SYMBOL        L?0532