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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.

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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

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How it works

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

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Configuration

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Site

Select the Worlds site to load available zones.

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Zone sequences

Define one or more sequences to check for. Each sequence contains:
ParameterDescription
ZonesOrdered list of zone IDs. The first zone is the start, the last is the target zone.
Bypass ZonesOptional. 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.

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Match mode

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

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Advanced settings

ParameterDefaultDescription
Check TargetAutoauto uses history + active for streaming, history only for batch
Debug ModefalseEnable verbose logging

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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.

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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": []
        }
      ]
    }
  }
}

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Key output fields

FieldDescription
passedWhether any configured sequence was found in the track’s zone history
matching_zonesTarget zones (last zone) of matching sequences
track_sequenceThe full zone sequence the track traversed
sequencesPer-sequence results with match positions, intermediate zones, and bypass zone details
reasonIf failed: no_sequences_configured, empty_track_sequence, no_sequences_matched, etc.

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Business use case examples

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.
ParameterValue
Sequence[Approach Zone, Target Zone]
Bypass ZonesNone
Match ModeOrdered
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.
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.
ParameterValue
Sequences13 zone pairs — [approach zone, stop zone] for each directional stop sign
Bypass ZonesNone
Match ModeOrdered
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:
GroupRequired 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.
Zone sequences can model any path-based validation:
Use CaseSequence DefinitionNotes
Wrong-way detection[Approach, Target] in wrong directionPassing = violation
Directional compliance[Approach, Checkpoint] in correct directionPassing = 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.

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Credentials

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