what does this do ?

ishare <[email protected]> Mon, 4 Mar 2013 01:21:04 +0800

Newsgroups	org.kernel.vger.linux-assembly
Message-ID	<[email protected]>


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 do they  mean?

thanks!