# LDC-E1312 — Transition to an undeclared state

## What it means

A transition moves between states of its own procedure: both ends must
name states that procedure declares, and a transition missing an end
declares no move at all. An endpoint the procedure never declared
points nowhere, so the compiler stops at the unknown name.

The repair is a spelling check against the state list: fix the name,
declare the missing state, or complete the transition with both ends.
Every endpoint then lands on a state that exists.

## Example

```law
language "law.core" version "0.2";
package demo.diagnostics version "0.1.0";
namespace "urn:law:demo:diagnostics";

entity Tenant;
procedure Review(t: Tenant) {
    state Open initial;
    state Closed terminal;
    transition Decide {
        from Open;
        to Missing;
    }
}
```

## Fix

```law
language "law.core" version "0.2";
package demo.diagnostics version "0.1.0";
namespace "urn:law:demo:diagnostics";

entity Tenant;
procedure Review(t: Tenant) {
    state Open initial;
    state Closed terminal;
    transition Decide {
        from Open;
        to Closed;
    }
}
```

## Engine message

The engine reports this in its own wording:

```text
example.law:11:12: error LDC-E1312: transition "Decide": state "Missing" is not declared in the procedure (§160)
```

## Related

- [Procedures](/constructs/procedure/) — states, transitions, and how a procedure runs.
- [LDC-E1313](/diagnostics/LDC-E1313/) — no transition may leave a terminal state.