Clarification on CVS Tags

[Jason Williams]

Good morning everyone.

I was hoping to get some verification regarding CVS Tags. I'm pretty sure I 
understand, but just wanted to have my thoughts validated for me.

In reading the CVS Tag page in the handbook, I understand the basics of 
what is going on.

If I specify this in my cvsup file:
RELENG_4_8

I will follow the Release Branch of 4.8, plus security patches.
This would be a good choice for production servers.


RELENG_4
For this, you are following the entire 4.x stable branch. In theory, if I 
install 4.5 and set this up in my cvsup file and run it, I will have the 
source tree going all the way to 4.9rc# correct? From here, you could build 
world?

Finally:

RELENG_4_8_0_RELEASE

This would follow just the source, ports and docs tree up to 4.8, the 
"frozen" section, correct?
Why would someone want to use this particular setup? What are the benefits? 
Drawbacks?
Would it work in a sense that if I installed 4.4 on a server, set this up 
in my cvsup file to RELENG_4_8_0_RELEASE, ran the update to update sources, 
ports and docs, then make world: That then would make my box 4.8 ?

I appreciate everyones help and insight.
Just want to make sure I understand this correctly.

Thanks.

Jason