Cache Memory in top command

[vyaaghrah-nix at yahoo.com]

Hi Everybody 

How is Cache memory in the following output calculated, on Free BSD system.

last pid: 39307;  load averages:  0.00,  0.00,  
0.00                                                                                                                       
 up 60+18:16:49  10:00:17
25 processes:  1 running, 24 sleeping
CPU states:  0.0% user,  0.0% nice,  0.0% system,  0.0% interrupt,  100% idle
Mem: 12M Active, 171M Inact, 68M Wired, 36K Cache, 111M Buf, 750M Free
Swap: 4000M Total, 4000M Free

 
Regards
Abhijeet.C