Version Management Utilities?

[Katsu Suzuki]

Hi, evryone. I am now developping big fortran program on Unix and
I read in somewhere that there is utilities to manage version of
source codes. (for example, you can retrieve version 1.0, 1.1, 1.2 etc
without taking up disk space for each source code.) Is that standard
unix? If so, what is the name of the commands? Or is that anonymous ftp-able
from somewhere? I mainly use Sun 3. 

Please e-mail me, and if anybody is also interested, drop me a line and I will
send answer if I got any.

Thanks in advance.

Katsu