[quonn]

It's a fork of the underlying MSHTML engine, that adds some new standard support and more importantly throws out the old compatibility modes and other legacy.

It will run in parallel to IE, which is here to stay for enterprise customers.

[manigandham]

It's a complete rebuilt engine called EdgeHTML, it's not hosting the old MSHTML engine anymore. IE will still be around as a browser program (with updates) for those who need it (enterprises, etc).

[Touche]

> It's a fork of the underlying MSHTML engine, that adds some new standard support

There's always new standards, so of course there is new standard support, just as IE is getting new standard support.

Effectively it is a redesign and rebranding of IE. Nothing wrong with that, but let's call a spade a spade.

[manigandham]

It's not a redesign, it's a completely new browser built clean and based on EdgeHTML.

IE will still be around as a separate browser that can be used in environments it's needed but Spartan/Edge is completely new and the way forward for the mainstream users.

http://blogs.msdn.com/b/ie/archive/2015/03/24/updates-from-t...

[icebraining]

No, it's not completely new from scratch:

So we set about to create a new engine using IE11’s standards support as a baseline. I watched Justin Rogers, one of our engineers, press “Enter” on the commit that forked the engine—it took almost 45 minutes just to process it (just committing the changes, not building!).

http://www.smashingmagazine.com/2015/01/26/inside-microsofts...

[manigandham]

At the risk of getting pedantic... they basically deleted the majority of it.

>> In the coming months, swathes of IE legacy were deleted from the new engine. Gone were document modes. Removed was the subsystem responsible for emulating IE8 layout quirks. VBScript eliminated. Remnants like attachEvent, X-UA-Compatible, currentStyle were all purged from the new engine. The codebase looks little like Trident anymore (far more diverged already than even Blink is from WebKit). What remained was a clean slate.

At this point, they kept basic stuff any rendering engine would do but it's as clean a start as you can get.

[icebraining]

A clean engine is Servo. This just sounds like cleaning up the codebase.

[manigandham]

Cleaning up implies they didn't add anything else. This is a major reworking that changes the entire stack.

Do they have to write every single line from scratch again? That would be an enormous waste of time. Even if they started with a completely new repo, they would just copy/paste that stuff anyway. The important bits are all new and that's what matters.

[chinpokomon]

It's a Ship of Theseus[1]. You can call it a derivative of IE, but that is doing a disservice to what Edge has become.

[1] http://en.m.wikipedia.org/wiki/Ship_of_Theseus

[fishfacemcgee]

It is IE12 with non of the legacy IE support. Their talk of update speed suggests it'll resemble Chrome and Firefox in terms of updates.