> ## Documentation Index
> Fetch the complete documentation index at: https://docs.vetrasuite.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Groups, anchors and pivots

> A market stall is one thing you built, not forty props. Groups let you treat it that way.

A **group** is a named set of up to **512** managed objects, plus an **anchor**: a
position and orientation that defines where the group *is*.

Every member is stored relative to that anchor. Move the anchor, and the whole structure
moves with it, keeping its internal geometry exactly.

## Creating one

<Steps>
  <Step title="Open Objects">
    The **Objects** section lists everything currently managed on this map, filterable by
    adapter and type.
  </Step>

  <Step title="Select the members">
    Pick the props, NPCs and other managed objects that make up the thing you built.
  </Step>

  <Step title="Create group">
    Name it. Blueprints computes a default anchor and stores each member's offset from it.
  </Step>
</Steps>

## The anchor

The default anchor is computed from the **bounds** the members recorded, not from their
origins.

That distinction is worth a sentence, because it is the difference between a group that
sets down correctly and one that does not. A model's origin is wherever the modeller put
it, so the lowest *origin* in a set of props is often the centre of a fridge. Dropping that
on a floor buries the fridge to its waist. Using recorded bounds puts the bottom of the
structure at the bottom of the structure.

<Note>
  Bounds come from the server that captured the objects, not from whatever copy of a model
  the admin's client happens to have installed. That is deliberate: placement is computed
  from the numbers your server recorded.
</Note>

### Move Anchor

Repositions the anchor and recomputes every member offset so that **nothing in the world
moves**. It is a document operation: it changes where you will hold the group next time,
not where the group is.

Use it when the default anchor is in an awkward place. Put it at the doorway of the
building, at the corner of the plot, at the base of the tower.

### Move Group

Plans new world transforms for every member from the offsets they already have, and applies
them.

This is the destructive one, and it runs in two phases like everything else: everything is
validated before anything is written, so a member that cannot be moved stops the operation
rather than leaving half a structure somewhere new.

## Resolving members

A group is a list of object **ids**. When you act on it, Blueprints has to find the real
objects those ids name, and it will not guess.

A member that cannot be resolved is reported with one of exactly three reasons:

| Reason            | What happened                                                                                                         | What to do                                                                  |
| ----------------- | --------------------------------------------------------------------------------------------------------------------- | --------------------------------------------------------------------------- |
| `cross_session`   | The member was recorded in a server session that has ended, and its adapter only guarantees identity within a session | Recapture the group's members on this session                               |
| `adapter_missing` | The adapter that owned it is not installed here                                                                       | Install the addon, or accept that the domain is out of scope on this server |
| `not_present`     | The object is simply gone from the world                                                                              | Recreate it, or remove the member                                           |

The list is closed on purpose. An open one would eventually grow a "probably the same
object" reason, and that is exactly the heuristic the identity contract exists to forbid.

## Recapturing a member

When you have deliberately moved one member of a group and want that to be its new resting
position, **recapture** it. That re-reads its current world transform into the group's
stored offset.

It is explicit and user-invoked so that drift is recorded on purpose rather than baked in
silently by the next move.

## What groups are for

Groups are the unit that [Migration](/blueprints/migration) and
[Deploy](/blueprints/deploy) operate on. A migration rebuilds a group somewhere else; a
deployment scope is a list of groups and standalone objects. Building good groups is what
makes both of those workable.