What exactly is this used for?

To upgrade your account, obviously. Ok, I'll explain more. It upgrades an account which used the older logon system to use the newer logon system. I don't think it's been seen at all yet since only Warcraft III is using the newest logon system, although, Diablo II and Starcraft support it.

I still don't get it.

There are 2 login systems...

The old login system
and the new login system

the only client to use the new login system is Warcraft III

But starcraft and Diablo 2 also support client update, presumable so they can be updated to the new login system at some point in time.

get it now?

In actuallity there are 3 login systems, the other one is used with the CHAT client.

[quote author=BaDDBLooD link=board=17;threadid=8390;start=0#msg77438 date=1093547444]
I still don't get it.
[/quote]

Warcraft III used to use a different login system, some accounts that were created with this older login system are still around, so they need to be upgraded for the new login system. Unless this is done, you cannot log on the account.

So Starcraft and d2 have "Support" to be upgraded, just isn't in effect yet.
What about Warcraft II?
When was the "OLD" Login system for wc3 used? Has anyone had to upgrade before?

[quote author=BaDDBLooD link=board=17;threadid=8390;start=0#msg77447 date=1093549421]
So Starcraft and d2 have "Support" to be upgraded, just isn't in effect yet.
What about Warcraft II?
When was the "OLD" Login system for wc3 used? Has anyone had to upgrade before?
[/quote]

Remember when Warcraft III Beta was out? Right now there are 3 login systems. Old products, W3 Beta, New Logon System (W3, W3XP).

I believe W3 (non beta) started out using the connection that the beta used, then they decied to upgrade the logon system.

So sometime in the future ( presumably ) starcraft/diablo2 will logon like war3/war3xp?

[quote author=BaDDBLooD link=board=17;threadid=8390;start=0#msg77449 date=1093549788]
So sometime in the future ( presumably ) starcraft/diablo2 will logon like war3/war3xp?
[/quote]

I think the reason these have this feature is because they used to logon using the 0x1E connection, until it was also upgraded. But the W2 client still uses the 0x1E connection, so no upgrade is necessary for W2.

[quote author=BaDDBLooD link=board=17;threadid=8390;start=0#msg77449 date=1093549788]
So sometime in the future ( presumably ) starcraft/diablo2 will logon like war3/war3xp?
[/quote]
Perhaps.

[quote author=ChRoNiC link=board=17;threadid=8390;start=0#msg77450 date=1093550084]
I think the reason these have this feature is because they used to logon using the 0x1E connection, until it was also upgraded. But the W2 client still uses the 0x1E connection, so no upgrade is necessary for W2.
[/quote]

I don't think Diablo II ever supported using BNCS packet 0x1E. What Skeptical said sounds about correct.

Should i handle account upgrade in my bot?

[quote author=BaDDBLooD link=board=17;threadid=8390;start=0#msg77473 date=1093559802]
Should i handle account upgrade in my bot?
[/quote]

It depends. ArmaBot Alpha 3 did not; it simply disconnected saying that "Battle.net requires that you update your account, which you must use an official client for." Alpha 4 does -- it will call an event saying that "Battle.net requires that you upgrade your account. Attempting upgrade..." and sends the appropriate data to/from BNLS and BNCS.

I've had several accounts, none of which I've seen do that. But it's there nonetheless.

[quote author=UserLoser. link=board=17;threadid=8390;start=0#msg77472 date=1093559677]What Skeptical said sounds about correct.
[/quote]

Duh, since he just reworded what you said. :P