> We currently have the trunk update stream, which is governed by update maps
> called 'update' in the source.squeak.org/trunk repository. This update
> stream is applicable to Squeak images up to the initial release of the
> Squeak 4.6 image. These are images in the non-Spur image formats (6504
> or 6505 for 32-bit images, and 68002 for a 64-bit image).

The .spur branch has already been collapsed onto trunk.  There is no
way to advance a non-spur image except through commits to the release
repositories (e.g., 'squea46').

> During the development period leading up to Squeak 5.0, which uses the
> new Spur image (format number 6521 for the 32-bit Spur image), the
> update stream has been governed by update maps called 'update.spur' in
> source.squeak.org/trunk.
>
> For Squeak 5.0, the update stream will continue to be governed by update
> maps called 'update' in the source.squeak.org/trunk repository. Users of
> Squeak 5.0 will see a normal trunk update stream from that point forward,
> and will now be using the Spur image format.

Yes.

> For Squeak 4.6, the update stream will continue to be called 'update',
> but will now be in the source.squeak.org/squeak46 repository. These update
> maps are not yet in the squeak46 repository,

I just made the first one in 'squeak46'.

> but will be added as required.
> The Squeak 4.6 release image points to this update stream. An effort will
> be made to keep the squeak46 update stream in sync with trunk through the
> next Squeak release cycle.

Oh really, who is going to do that?

> For an existing trunk image, such as a Squeak 4.5 image that has been kept
> up to date with the trunk, it will be necessary to switch from
> source.squeak.org/trunk with update map name 'update', to a new setting
> of source.squeak.org/squeak46 with update map name 'update', This change
> must be made more or less concurrently with the Squeak 5.0 release.
>
> Questions:
>
> 1) Is the above summary correct?
>
> 2) Is it possible for the trunk update stream to force an existing trunk
> image (originating from Squeak 4.5 or earlier) to switch over to the squeak46
> repository automatically, such that updates can proceed without loading
> Spur-specific changes into a non-Spur trunk image?

You would need to make sure not to update past update-topa.322.mcm.
Probably the code is not set up to do a limited updated.

No, you have to update the updateURL in Preferences.

> 3) Previously, the release-specific repository (e.g. source.squeak.org/squeak45
> for Squeak 4.5) was used for applying a few important fixes to a stable
> release. Assuming that this is also the intent for Squeak 4.6, and that we
> also want to make an effort to permit non-Spur images to stay in sync with
> trunk for some period of time (nominally one release cycle), then would it
> be helpful to consider providing a trunk-compatible update stream for non-Spur
> images during the transition period? I am not sure how that should work
> (possibly something involving an 'update.classic' update map), but I would
> like to know if conceptually it is something we should be trying to do.

Basically you are talking about a fork of Squeak.  Unless someone has
some kind of compatibility issue with their application, I don't know
why anyone would want to expend resources maintaining an old fork..