Type II: Zone Sequence

Type II checks evaluate whether a track traversed zones in a configured sequence. This is used for detecting directional violations, validating expected paths, or identifying tracks that skipped required checkpoints.

When to use

Use Type II for any use case where the core question is “did this object travel through zones in this order?”:

Wrong-way detection — track visited zones in the reverse of the expected direction
Checkpoint validation — track passed through required zones before entering a restricted area
Path compliance — track followed the expected route through a facility
Entry/exit patterns — track entered through a specific zone and exited through another

How it works

The node builds the track’s zone sequence — the chronological order of zones visited
For each configured sequence, it checks if the zones appear in that order within the track sequence
Bypass zones can invalidate a match if they appear between sequence zones
The check passes if at least one configured sequence matches

Configuration

Site

Select the Worlds site to load available zones.

Zone sequences

Define one or more sequences to check for. Each sequence contains:

Parameter	Description
Zones	Ordered list of zone IDs. The first zone is the start, the last is the target zone.
Bypass Zones	Optional. Zones that invalidate the match if visited between sequence zones.

Each sequence requires at least 2 zones. The last zone in the sequence is the target zone — it gets added to matching_zones when the sequence matches.

Match mode

Mode	Description
Ordered (recommended)	Zones must appear in order, but other zones can appear between them. Sequence [A, C] matches in path [A, B, C].
Exact	The last N zones must match exactly. Sequence [A, C] only matches if the last 2 zones visited are [A, C] with nothing between.

Advanced settings

Parameter	Default	Description
Check Target	Auto	`auto` uses history + active for streaming, history only for batch
Debug Mode	false	Enable verbose logging

Bypass zones

Bypass zones provide a way to invalidate a sequence match. If a track visited a bypass zone between any two zones in the sequence, the match is invalidated. Example — wrong-way detection with exception:

Sequence: [Zone A, Zone B] (expected forward direction)
Bypass zones: [Security Checkpoint]
Track path: Zone A → Security Checkpoint → Zone B
Result: No match — the security checkpoint between A and B invalidates the sequence

This is useful for cases where a specific intermediate zone means the traversal was authorized.

Output

{
  "track_state": { ... },
  "checks": {
    "type2": {
      "passed": true,
      "check_target": "active",
      "check_target_source": "auto",
      "matching_zones": ["zone_b"],
      "matching_zone_count": 1,
      "track_sequence": ["zone_a", "zone_c", "zone_b"],
      "sequences": [
        {
          "zones": ["zone_a", "zone_b"],
          "target_zone": "zone_b",
          "passed": true,
          "match_positions": [0, 2],
          "intermediate_zones": ["zone_c"],
          "bypass_zones_found": []
        }
      ]
    }
  }
}

Key output fields

Field	Description
`passed`	Whether any configured sequence was found in the track’s zone history
`matching_zones`	Target zones (last zone) of matching sequences
`track_sequence`	The full zone sequence the track traversed
`sequences`	Per-sequence results with match positions, intermediate zones, and bypass zone details
`reason`	If failed: `no_sequences_configured`, `empty_track_sequence`, `no_sequences_matched`, etc.

Business use case examples

Wrong-way detection — single zone sequence

Detect vehicles traveling in the wrong direction through one-way aisles. Each sequence defines an approach zone and a target zone representing the wrong direction.

Parameter	Value
Sequence	[Approach Zone, Target Zone]
Bypass Zones	None
Match Mode	Ordered

Mode: Batch — only need the track summary after the vehicle passes through.If a vehicle visits the approach zone before the target zone (in the wrong direction), the sequence matches and the check passes. Multiple sequences can be configured for different one-way aisles across the site.

Define the sequence in the wrong direction. The check passing means the violation occurred.

Failure to stop — directional stop sign enforcement

In the failure-to-stop compliance workflow, Type II is composed with Type I to enforce directional stop signs — stop signs that only apply when approaching from a specific direction.

Parameter	Value
Sequences	13 zone pairs — [approach zone, stop zone] for each directional stop sign
Bypass Zones	None
Match Mode	Ordered

Mode: Batch — composed with a Type I velocity check upstream.The Type II check answers: “did this vehicle come from the approach direction before reaching the stop zone?” This is combined with the Type I velocity check via a Check Aggregator that defines two groups:

Group	Required Checks
Directional stop signs (12 zones)	Type I + Type II
Non-directional stop signs (4 zones)	Type I only

This demonstrates how Type II is often a secondary check that adds directional context to a primary check, rather than standing alone.

Adapting for other use cases

Zone sequences can model any path-based validation:

Use Case	Sequence Definition	Notes
Wrong-way detection	[Approach, Target] in wrong direction	Passing = violation
Directional compliance	[Approach, Checkpoint] in correct direction	Passing = compliant
Checkpoint validation	[Entry, Checkpoint A, Checkpoint B, Destination]	Multi-step sequence
Restricted access	[Public Area, Restricted Zone]	With bypass zone for authorized paths

Use bypass zones when certain intermediate zones should invalidate the match — for example, passing through a security checkpoint between zones means the traversal was authorized.

Credentials

Requires GraphQL Subscription API credentials (for loading site/zone options).

Trigger Nodes

Check Nodes

Event Nodes

Action Nodes

When to use

How it works

Configuration

Site

Zone sequences

Match mode

Advanced settings

Bypass zones

Output

Key output fields

Business use case examples

Credentials

​When to use

​How it works

​Configuration

​Site

​Zone sequences

​Match mode

​Advanced settings

​Bypass zones

​Output

​Key output fields

​Business use case examples

​Credentials

When to use

How it works

Configuration

Site

Zone sequences

Match mode

Advanced settings

Bypass zones

Output

Key output fields

Business use case examples

Credentials