fstab 필드별 내용이 어떤건지 모르겠어요

/dev/sda3                        /                            ext3     defaults        1 1
LABEL=/backup            /backup                 ext3     defaults        1 2
1첫번째 필드 : LABEL=/backup로 하는 /dev/sda2의 장치인데
첫줄하고 차이점이 있나요.

none                               /dev/pts                 devpts   gid=5,mode=620  0 0
none                               /proc                     proc     defaults        0 0
none                               /dev/shm                tmpfs    defaults        0 0
none은 어떤건지 꼭 있어야 하는건지요

LABEL=/var                  /var                        ext3     defaults        1 2
/dev/sda5                       swap                       swap    defaults        0 0
/dev/cdrom                     /mnt/cdrom             udf,iso9660 noauto,owner,kudzu,ro 0 0
/dev/fd0                         /mnt/floppy               auto    noauto,owner,kudzu 0 0
none 끝필드에 0,0은 어떤 의미인지.

각필드마다 설명부탁드려요...너무너무 초보가..////