diff --git a/game/sidc.py b/game/sidc.py
new file mode 100644
index 00000000..7ae4ace2
--- /dev/null
+++ b/game/sidc.py
@@ -0,0 +1,276 @@
+"""Implements Symbol Identification Codes (SIDCs) as defined by NATO APP-6(D).
+
+This implementation only covers assembly of the identifier strings. The front-end is
+responsible for drawing the icons.
+
+The third ten digits (used for national modifications and additions not covered by
+APP-6) are not implemented. The third set of ten digits are optional and will be omitted
+from the output.
+
+https://nso.nato.int/nso/nsdd/main/standards/ap-details/1912/EN
+https://www.spatialillusions.com/milsymbol/docs/milsymbol-2525d.html
+"""
+from __future__ import annotations
+
+from dataclasses import dataclass
+from enum import IntEnum, unique
+
+# Version field defined by A.5.
+VERSION = 10
+
+
+@unique
+class Context(IntEnum):
+    """Context field defined by A.6.."""
+
+    REALITY = 0
+    EXERCISE = 1
+    SIMULATION = 2
+    # 3-9 are reserved for future use.
+
+    def __str__(self) -> str:
+        return str(self.value)
+
+
+@unique
+class StandardIdentity(IntEnum):
+    """Standard identity field defined by A.6."""
+
+    PENDING = 0
+    UNKNOWN = 1
+    ASSUMED_FRIEND = 2
+    FRIEND = 3
+    NEUTRAL = 4
+    SUSPECT_JOKER = 5
+    HOSTILE_FAKER = 6
+    # 7-9 are reserved for future use.
+
+    def __str__(self) -> str:
+        return str(self.value)
+
+
+@unique
+class SymbolSet(IntEnum):
+    """Symbol set field defined by A.7."""
+
+    UNKNOWN = 0
+    AIR = 1
+    AIR_MISSILE = 2
+    SPACE = 5
+    SPACE_MISSILE = 6
+    LAND_UNIT = 10
+    LAND_CIVILIAN_UNIT_ORGANIZATION = 11
+    LAND_EQUIPMENT = 15
+    LAND_INSTALLATIONS = 20
+    CONTROL_MEASURE = 25
+    DISMOUNTED_INDIVIDUAL = 27
+    SEA_SURFACE = 30
+    SEA_SUBSURFACE = 35
+    MINE_WARFARE = 36
+    ACTIVITY_EVENT = 40
+    ATMOSPHERIC = 45
+    OCEANOGRAPHIC = 46
+    METEOROLOGICAL_SPACE = 47
+    SIGNALS_INTELLIGENCE_SPACE = 50
+    SIGNALS_INTELLIGENCE_AIR = 51
+    SIGNALS_INTELLIGENCE_LAND = 52
+    SIGNALS_INTELLIGENCE_SURFACE = 53
+    SIGNALS_INTELLIGENCE_SUBSURFACE = 54
+    CYBERSPACE_SPACE = 60
+    CYBERSPACE_AIR = 61
+    CYBERSPACE_LAND = 62
+    CYBERSPACE_SURFACE = 63
+    CYBERSPACE_SUBSURFACE = 64
+    VERSION_EXTENSION_FLAG = 99
+    # All other values reserved for future use.
+
+    def __str__(self) -> str:
+        return f"{self.value:02}"
+
+
+@unique
+class Status(IntEnum):
+    """Status field defined by A.8 Status."""
+
+    PRESENT = 0
+    PLANNED_ANTICIPATED_SUSPECT = 1
+    PRESENT_FULLY_CAPABLE = 2
+    PRESENT_DAMAGED = 3
+    PRESENT_DESTROYED = 4
+    PRESENT_FULL_TO_CAPACITY = 5
+    # 6-8 reserved for future use.
+    VERSION_EXTENSION_FLAG = 9
+
+    def __str__(self) -> str:
+        return str(self.value)
+
+
+@unique
+class HeadquartersTaskForceDummy(IntEnum):
+    """Headquarters/Task Force/Dummy field defined by A.9."""
+
+    NOT_APPLICABLE = 0
+    FEINT_DUMMY = 1
+    HEADQUARTERS = 2
+    FEINT_DUMMY_HEADQUARTERS = 3
+    TASK_FORCE = 4
+    FEINT_DUMMY_TASK_FORCE = 5
+    TASK_FORCE_HEADQUARTERS = 6
+    FEINT_DUMMY_TASK_FORCE_HEADQUARTERS = 7
+    # 8 reserved for future use.
+    VERSION_EXTENSION_FLAG = 9
+
+    def __str__(self) -> str:
+        return str(self.value)
+
+
+@unique
+class Amplifier(IntEnum):
+    """Unit Echelon/Equipment Mobility/Naval Towed Array Amplifier defined by A.10"""
+
+    UNKNOWN = 0
+
+    # Echelon at brigade and below
+    TEAM_CREW = 11
+    SQUAD = 12
+    SECTION = 13
+    PLATOON_DETACHMENT = 14
+    COMPANY_BATTERY_TROOP = 15
+    BATTALION_SQUADRON = 16
+    REGIMENT_GROUP = 17
+    BRIGADE = 18
+    VERSION_EXTENSION_FLAG = 19
+
+    # Echelon at brigade and above
+    DIVISION = 21
+    CORP_MARINE_EXPEDITIONARY_FORCE = 22
+    ARMY = 23
+    ARMY_GROUP_FRONT = 24
+    REGION_THEATRE = 25
+    COMMAND = 26
+    # 27-28 reserved for future use.
+    VERSION_EXTENSION_FLAG2 = 29
+
+    # Equipment mobility on land
+    WHEELED_LIMITED_CROSS_COUNTRY = 31
+    WHEELED_CROSS_COUNTRY = 32
+    TRACKED = 33
+    WHEELED_AND_TRAKCED_COMBINATION = 34
+    TOWED = 35
+    RAIL = 36
+    PACK_ANIMALS = 37
+    # 38 reserved for future use.
+    VERSION_EXTENSION_FLAG3 = 39
+
+    # Equipment mobility on snow
+    OVER_SNOW = 41
+    SLED = 42
+    # 3-8 reserved for future use.
+    VERSION_EXTENSION_FLAG4 = 49
+
+    # Equipment mobility on water
+    BARGE = 51
+    AMPHIBIOUS = 52
+    # 3-8 reserved for future use.
+    VERSION_EXTENSION_FLAG5 = 59
+
+    # Naval towed array
+    SHORT_TOWED_ARRAY = 61
+    LONG_TOWED_ARRAY = 62
+    # 3-8 reserved for future use.
+    VERSION_EXTENSION_FLAG6 = 69
+
+    # Leadership indicator
+    LEADER_INDIVIDUAL = 71
+    DEPUTY_INDIVIDUAL = 72
+    # 3-8 reserved for future use.
+    VERSION_EXTENSION_FLAG7 = 79
+
+    # 80-89 reserved for future use.
+    # 90-99 version extension flag.
+
+    def __str__(self) -> str:
+        return f"{self.value:02}"
+
+
+class Entity(IntEnum):
+    def __str__(self) -> str:
+        return f"{self.value:06}"
+
+
+# Entity types (the second set of ten digits are implemented as-needed. These are
+# defined by section A.13. Entity/Entity Type/Entity Subtype and Sector 1 and Sector 2
+# Modifiers. The specific entity enum used by the SIDC depends on the symbol set used.
+@unique
+class AirEntity(Entity):
+    """Air Entity/Entity Type/Entity Subtype defined by table A-10."""
+
+    UNSPECIFIED = 0
+
+
+@unique
+class LandInstallationEntity(Entity):
+    """Land Installation Entity/Entity Type/Entity Subtype defined by table A-27."""
+
+    UNSPECIFIED = 0
+
+    MILITARY_BASE = 120802
+    AIPORT_AIR_BASE = 121301
+
+
+@unique
+class SeaSurfaceEntity(Entity):
+    """Sea Surface Entity/Entity Type/Entity Subtype defined by table A-34."""
+
+    UNSPECIFIED = 0
+
+    CARRIER = 120100
+    AMPHIBIOUS_ASSAULT_SHIP_GENERAL = 120303
+
+
+@unique
+class UnknownEntity(Entity):
+    """Fallback entity type used when the symbol set is not known."""
+
+    UNSPECIFIED = 0
+
+
+class Modifier(IntEnum):
+    """Fallback modifier used when the symbol set is not known."""
+
+    UNSPECIFIED = 0
+
+    def __str__(self) -> str:
+        return f"{self.value:02}"
+
+
+@dataclass
+class SymbolIdentificationCode:
+    version = VERSION
+    context: Context = Context.REALITY
+    standard_identity: StandardIdentity = StandardIdentity.UNKNOWN
+    symbol_set: SymbolSet = SymbolSet.UNKNOWN
+    status: Status = Status.PRESENT
+    headquarters_task_force_dummy: HeadquartersTaskForceDummy = (
+        HeadquartersTaskForceDummy.NOT_APPLICABLE
+    )
+    amplifier: Amplifier = Amplifier.UNKNOWN
+    entity: Entity = UnknownEntity.UNSPECIFIED
+    sector_one_modifier = Modifier.UNSPECIFIED
+    sector_two_modifier = Modifier.UNSPECIFIED
+
+    def __str__(self) -> str:
+        return "".join(
+            [
+                f"{self.version:02}",
+                str(self.context),
+                str(self.standard_identity),
+                str(self.symbol_set),
+                str(self.status),
+                str(self.headquarters_task_force_dummy),
+                str(self.amplifier),
+                str(self.entity),
+                str(self.sector_one_modifier),
+                str(self.sector_two_modifier),
+            ]
+        )
diff --git a/tests/test_sidc.py b/tests/test_sidc.py
new file mode 100644
index 00000000..6c6fac36
--- /dev/null
+++ b/tests/test_sidc.py
@@ -0,0 +1,17 @@
+from game.sidc import (
+    LandInstallationEntity,
+    StandardIdentity,
+    Status,
+    SymbolIdentificationCode,
+    SymbolSet,
+)
+
+
+def test_sidc() -> None:
+    sidc = SymbolIdentificationCode(
+        standard_identity=StandardIdentity.FRIEND,
+        symbol_set=SymbolSet.LAND_INSTALLATIONS,
+        status=Status.PRESENT_DAMAGED,
+        entity=LandInstallationEntity.AIPORT_AIR_BASE,
+    )
+    assert str(sidc) == "10032030001213010000"