FreeBSD files' heads

[CBuH.]

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Hello, all.

I've got a question (easier -- ``interesting in'') -- why all FreeBSD files' 
heads starts with this:

# $FreeBSD: src/etc/shells,v 1.3.2.1 2000/07/10 08:47:17 obrien Exp $

- - Why there are buks (am I pronounce right ? :-) ``$'' -- on the start & end 
of this string?
- - And what do mean ``Exp'' at the end?

10x alot,... 

- -- 

        CBuH. CG[CX] XVyGYjau 479001600 at mail.ru, ICQ#70929413
	GnuPG(PGP) public key is: http://ccclike.chat.ru/my_public_key.asc

	
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