What does IDS/IDW mean and what are Escrow builds?

I have noticed a lot of questions and confusion regarding IDS builds recently. In the following I’ll give you a small overview of the different developer builds and what their abbrevations mean.

There are 3 kinds of these developer builds, which are:

IDW – Internal Developer Workstation
IDS – Internal Developer Server

Originally the IDW term was used to describe a build which can be used as a workstation and the IDS term was used to describe a build wich can be used as a server inside Microsoft “without too much pain”. Later, this connotation has changed and these builds have been seperated into two “tiers”: IDW for unstable builds and IDS for builds which are a bit more stable than IDW builds, but not as stable as beta builds.
Today, the term IDW is used for CTPs and stuff like this and the term IDS is used to describe unstable builds, or builds of a “helper-branch” (for example winmain_win7ids).
To avoid confusion between IDW and IDS, the IDX term (Internal Developer Client/Server) is for generally unstable builds, which do not have beta quality already. Oddly, during Windows 7 development the IDX term was used for builds with pre-RC quality.

Here is a quote a guy from the WSSG (Windows Server Solutions Group) made once:

This milestone is termed the “Internal Developer Server” (IDS) build – it’s
an internal quality term we use meaning that the build is stable enough to
deploy and evaluate, but may contain more minor bugs than a Beta build.
You’ll run into some unedited UI stings, and some bugs that we purposefully
chose not to fix until later in the development cycle. It’s a tradeoff we’ve
made to ensure we keep getting great feedback without unduly delaying the

EDW – External Developer Workstation

This term was used during the final development phase of Windows Vista (between RC and RTM) for builds which got released to the TAPs. I am not sure if this term has been used for anything else, but I think you can compare this with the IDX builds of Windows 7 (which represent something like an inofficial/internal Release Candidate).

Let me know if you have any anything to add.

What are Escrow builds?

(Update from 10. Jan, 2010)

Sometimes Microsoft released builds referred to as “Escrow”. Escrow means the development of a branch gets stopped and the code is being tested. If Microsoft or its testers don’t discover any serious bugs (“showstoppers”), the current build becomes the final milestone (usually RC or RTM, but sometimes there are also beta escrow builds). Escrow builds are usually handed out to TAP (Technology Adoption Program) testers, ISVs, IHVs, etc.

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