what does this do ?

[ishare <june.tune.sea@xxxxxxxxx>]

here are a portion of  build-in asm code  :

    "  .long 661b\n"                    \
    "  .long 663f\n"            \
    "  .byte %c0\n"             /               \
    "  .byte 662b-661b\n"                       \
    "  .byte 664f-663f\n"

what is 661b,663f ,etc .

what does it mean?

thanks!