IPV6 and ISP with Hex 2001

[zillah]

While I was reading through this documentation I found this :
http://www.tdoi.org/mirrors/bieringer/Linux+IPv6-HOWTO/x530.html

3.2.3.3. Assigned by provider for hierarchical routing
These addresses are delegated to Internet service providers (ISP) and begin with
2001:

Is this (2001) special case for the link above ? or it is for all IPv6 addresses ?

 

[zillah]

Any idea about this issue ?

 

[Kumar]

I think its for all ISP backbone providers

These addresses are delegated to Internet service providers (ISP)