What is the difference between RES and PRES fields in linux procstat

What is the difference between RES and PRES fields in linux procstat

References

Reference NO 1

http://stackoverflow.com/questions/18175209/relation-between-init-and-bash-terminal-process

Reference NO 2

http://linux.die.net/man/5/proc

Reference NO 3

http://linux.about.com/od/commands/l/blcmdl5_proc.htm

Reference NO 4

http://www.linux.com/learn/tutorials/42048-uncover-the-meaning-of-tops-statistics

Reference NO 5

https://www.kernel.org/doc/Documentation/filesystems/proc.txt

Reference NO 6

http://en.wikipedia.org/wiki/Procfs

Reference NO 7

http://linuxvm.org/present/SHARE108/S9266cb.pdf

Reference NO 8

http://www.cs.fsu.edu/~baker/devices/lxr/http/source/linux/Documentation/filesystems/proc.txt