Kafka Core Protocol APIs
This document specifies the core Kafka protocol APIs used for message production, consumption, and cluster metadata. These APIs form the foundation of all Kafka client operations.
API Key Reference
Core APIs
| API Key |
Name |
Purpose |
| 0 |
Produce |
Send records to partitions |
| 1 |
Fetch |
Retrieve records from partitions |
| 2 |
ListOffsets |
Query offset by timestamp |
| 3 |
Metadata |
Discover cluster topology |
| 18 |
ApiVersions |
Query supported API versions |
Produce API (Key 0)
Overview
The Produce API sends record batches to topic partitions. It is the primary API for message production.
Version History
| Version |
Kafka |
Key Changes |
| 0 |
0.8.0 |
Initial version (removed in 4.0) |
| 3 |
0.11.0 |
Transactional ID + message format v2 (4.0 baseline) |
| 4 |
0.11.0 |
KAFKA_STORAGE_ERROR |
| 5 |
1.0.0 |
Log start offset in response |
| 7 |
2.1.0 |
Zstandard compression (KIP-110) |
| 8 |
2.3.0 |
Record errors + error message (KIP-467) |
| 9 |
2.4.0 |
Flexible versions |
| 10 |
3.7.0 |
Current leader + node endpoints (KIP-951) |
| 11 |
3.8.0 |
TRANSACTION_ABORTABLE (KIP-890) |
| 13 |
4.0.0 |
Topic IDs (KIP-516) |
Request Schema
ProduceRequest =>
transactional_id: NULLABLE_STRING
acks: INT16
timeout_ms: INT32
topic_data: [TopicData]
TopicData =>
name: STRING
topic_id: UUID
partition_data: [PartitionData]
PartitionData =>
index: INT32
records: RECORDS
Topic names are used through v12; v13+ uses topic_id instead.
| Field |
Type |
Description |
transactional_id |
NULLABLE_STRING |
Transaction ID (null for non-transactional) |
acks |
INT16 |
Required acknowledgments (-1, 0, 1) |
timeout_ms |
INT32 |
Request timeout in milliseconds |
topic_data |
ARRAY |
Per-topic record data |
partition_data |
ARRAY |
Per-partition record batches |
records |
RECORDS |
Record batch data |
Response Schema
ProduceResponse =>
responses: [TopicResponse]
throttle_time_ms: INT32
node_endpoints: [NodeEndpoint]
TopicResponse =>
name: STRING
topic_id: UUID
partition_responses: [PartitionResponse]
PartitionResponse =>
index: INT32
error_code: INT16
base_offset: INT64
log_append_time_ms: INT64
log_start_offset: INT64
record_errors: [RecordError]
error_message: NULLABLE_STRING
current_leader: LeaderIdAndEpoch
NodeEndpoint =>
node_id: INT32
host: STRING
port: INT32
rack: NULLABLE_STRING
| Field |
Type |
Description |
error_code |
INT16 |
Partition-level error |
base_offset |
INT64 |
Offset of first record in batch |
log_append_time_ms |
INT64 |
Timestamp (-1 if CreateTime) |
log_start_offset |
INT64 |
Log start offset |
record_errors |
ARRAY |
Per-record errors (v8+) |
throttle_time_ms |
INT32 |
Quota throttle time |
current_leader |
STRUCT |
Suggested leader for future requests (v10+) |
node_endpoints |
ARRAY |
Endpoint list for leaders in response (v10+) |
acks Semantics
| acks |
Name |
Guarantee |
Response |
| 0 |
Fire-and-forget |
None |
No response sent |
| 1 |
Leader |
Leader wrote to local log |
After leader persist |
| -1 |
All |
All ISR replicas wrote |
After ISR persist |
Behavioral Contract
| Aspect |
Guarantee |
| Ordering |
Records within a batch must be written in batch order |
| Atomicity |
Batch to single partition must succeed or fail atomically |
| Durability |
Depends on acks setting and min.insync.replicas |
| Idempotence |
With enable.idempotence, duplicates are prevented |
acks=0 No Response
With acks=0, the broker must not send a response. The client must not wait for a response. Delivery is not confirmed.
Error Handling
| Error Code |
Retriable |
Cause |
Recovery |
| NOT_LEADER_OR_FOLLOWER |
✅ |
Stale leader |
Refresh metadata, retry |
| REQUEST_TIMED_OUT |
✅ |
Broker timeout |
Retry with backoff |
| NOT_ENOUGH_REPLICAS |
✅ |
ISR too small |
Wait, retry |
| MESSAGE_TOO_LARGE |
❌ |
Record exceeds limit |
Reduce message size |
| TOPIC_AUTHORIZATION_FAILED |
❌ |
No Write permission |
Check ACLs |
| OUT_OF_ORDER_SEQUENCE_NUMBER |
❌ |
Sequence gap |
Fatal for idempotent |
Fetch API (Key 1)
Overview
The Fetch API retrieves record batches from topic partitions. It supports long-polling, session-based fetching, and transactional isolation.
Version History
| Version |
Kafka |
Key Changes |
| 0 |
0.8.0 |
Initial version (removed in 4.0) |
| 4 |
0.11.0 |
Isolation level (4.0 baseline) |
| 5 |
1.0.0 |
Log start offset |
| 7 |
1.1.0 |
Fetch sessions |
| 9 |
2.1.0 |
Current leader epoch (KIP-320) |
| 10 |
2.1.0 |
Zstandard support (KIP-110) |
| 11 |
2.3.0 |
Rack ID |
| 12 |
2.4.0 |
Flexible versions + last fetched epoch |
| 13 |
2.8.0 |
Topic IDs (KIP-516) |
| 14 |
3.4.0 |
Tiered storage offset moved (KIP-405) |
| 15 |
3.5.0 |
Replica state (KIP-903) |
| 16 |
3.7.0 |
Node endpoints (KIP-951) |
| 17 |
3.8.0 |
Replica directory ID (KIP-853) |
| 18 |
4.1.0 |
High-watermark in request (KIP-1166) |
Request Schema
FetchRequest =>
cluster_id: NULLABLE_STRING
replica_id: INT32
replica_state: ReplicaState
max_wait_ms: INT32
min_bytes: INT32
max_bytes: INT32
isolation_level: INT8
session_id: INT32
session_epoch: INT32
topics: [TopicRequest]
forgotten_topics_data: [ForgottenTopic]
rack_id: STRING
TopicRequest =>
topic: STRING
topic_id: UUID
partitions: [PartitionRequest]
PartitionRequest =>
partition: INT32
current_leader_epoch: INT32
fetch_offset: INT64
last_fetched_epoch: INT32
log_start_offset: INT64
partition_max_bytes: INT32
replica_directory_id: UUID
high_watermark: INT64
ReplicaState =>
replica_id: INT32
replica_epoch: INT64
Topic names are used through v12; v13+ uses topic_id instead.
| Field |
Type |
Description |
cluster_id |
NULLABLE_STRING |
Cluster ID for validation (v12+) |
replica_id |
INT32 |
Replica ID (-1 for consumers, v0-14) |
replica_state |
STRUCT |
Replica ID + epoch (v15+) |
max_wait_ms |
INT32 |
Maximum wait time for data |
min_bytes |
INT32 |
Minimum bytes to return |
max_bytes |
INT32 |
Maximum bytes to return |
isolation_level |
INT8 |
0=read_uncommitted, 1=read_committed |
session_id |
INT32 |
Fetch session ID (0 for new) |
fetch_offset |
INT64 |
Offset to fetch from |
last_fetched_epoch |
INT32 |
Last fetched epoch for fencing (v12+) |
partition_max_bytes |
INT32 |
Maximum bytes per partition |
forgotten_topics_data |
ARRAY |
Partitions to remove from session (v7+) |
rack_id |
STRING |
Consumer rack ID (v11+) |
Response Schema
FetchResponse =>
throttle_time_ms: INT32
error_code: INT16
session_id: INT32
responses: [TopicResponse]
node_endpoints: [NodeEndpoint]
TopicResponse =>
topic: STRING
topic_id: UUID
partitions: [PartitionResponse]
PartitionResponse =>
partition: INT32
error_code: INT16
high_watermark: INT64
last_stable_offset: INT64
log_start_offset: INT64
diverging_epoch: EpochEndOffset
current_leader: LeaderIdAndEpoch
snapshot_id: SnapshotId
aborted_transactions: [AbortedTransaction]
preferred_read_replica: INT32
records: RECORDS
EpochEndOffset =>
epoch: INT32
end_offset: INT64
SnapshotId =>
end_offset: INT64
epoch: INT32
| Field |
Type |
Description |
high_watermark |
INT64 |
End offset of committed data |
last_stable_offset |
INT64 |
End of non-transactional or committed data |
log_start_offset |
INT64 |
Log start offset |
aborted_transactions |
ARRAY |
Aborted transaction markers |
preferred_read_replica |
INT32 |
Suggested follower for reads |
records |
RECORDS |
Fetched record batches |
Isolation Levels
| Level |
Value |
Behavior |
read_uncommitted |
0 |
Returns all records up to high watermark |
read_committed |
1 |
Returns only committed records (filters aborted transactions) |
Long Polling
The Fetch API supports long polling via min_bytes and max_wait_ms:
Behavioral Contract
| Aspect |
Guarantee |
| Ordering |
Records returned in offset order per partition |
| Completeness |
All records in requested range (up to size limits) |
| Isolation |
With read_committed, no uncommitted transactional records |
| Freshness |
May return slightly stale data after leader change |
Error Handling
| Error Code |
Retriable |
Cause |
Recovery |
| OFFSET_OUT_OF_RANGE |
❌ |
Invalid fetch offset |
Reset to valid offset |
| NOT_LEADER_OR_FOLLOWER |
✅ |
Stale leader |
Refresh metadata, retry |
| UNKNOWN_TOPIC_OR_PARTITION |
✅ |
Topic not found |
Wait, retry |
| KAFKA_STORAGE_ERROR |
✅ |
Disk error |
Wait, retry different replica |
ListOffsets API (Key 2)
Overview
The ListOffsets API retrieves offsets by timestamp or special offset positions (earliest, latest).
Version History
| Version |
Kafka |
Key Changes |
| 0 |
0.8.0 |
Initial version (removed in 4.0) |
| 1 |
0.10.1 |
Single-offset response (4.0 baseline) |
| 2 |
0.11.0 |
Isolation level |
| 4 |
2.1.0 |
Leader epoch |
| 5 |
2.2.0 |
OFFSET_NOT_AVAILABLE |
| 6 |
2.4.0 |
Flexible versions |
| 7 |
2.8.0 |
MAX_TIMESTAMP (KIP-734) |
| 8 |
3.4.0 |
EARLIEST_LOCAL (KIP-405) |
| 9 |
3.6.0 |
LATEST_TIERED (KIP-1005) |
| 10 |
3.8.0 |
Remote list offsets (KIP-1075) |
| 11 |
4.0.0 |
EARLIEST_PENDING_UPLOAD (KIP-1023) |
Request Schema
ListOffsetsRequest =>
replica_id: INT32
isolation_level: INT8
topics: [TopicRequest]
timeout_ms: INT32
TopicRequest =>
name: STRING
partitions: [PartitionRequest]
PartitionRequest =>
partition_index: INT32
current_leader_epoch: INT32
timestamp: INT64
| Field |
Type |
Description |
replica_id |
INT32 |
Replica ID (-1 for consumers) |
isolation_level |
INT8 |
0=read_uncommitted, 1=read_committed |
timestamp |
INT64 |
Target timestamp or special value |
timeout_ms |
INT32 |
Timeout for remote tiered reads (v10+) |
Special Timestamp Values
| Value |
Name |
Meaning |
| -1 |
LATEST |
Latest offset (log end offset) |
| -2 |
EARLIEST |
Earliest offset (log start offset) |
| -3 |
MAX_TIMESTAMP |
Offset of record with max timestamp (v7+) |
| -4 |
EARLIEST_LOCAL |
Earliest local log offset (v8+) |
| -5 |
LATEST_TIERED |
Latest tiered storage offset (v9+) |
| -6 |
EARLIEST_PENDING_UPLOAD |
Earliest pending upload offset (v11+) |
| ≥0 |
Timestamp |
First offset with timestamp ≥ value |
Response Schema
ListOffsetsResponse =>
throttle_time_ms: INT32
topics: [TopicResponse]
TopicResponse =>
name: STRING
partitions: [PartitionResponse]
PartitionResponse =>
partition_index: INT32
error_code: INT16
timestamp: INT64
offset: INT64
leader_epoch: INT32
| Field |
Type |
Description |
timestamp |
INT64 |
Timestamp of returned offset (-1 if none) |
offset |
INT64 |
Found offset |
leader_epoch |
INT32 |
Leader epoch of returned offset |
Behavioral Contract
| Aspect |
Guarantee |
| Timestamp lookup |
Returns first offset where record timestamp ≥ requested |
| EARLIEST |
Returns log start offset |
| LATEST |
Returns high watermark (read_uncommitted) or LSO (read_committed) |
| Not found |
Returns -1 for offset if no matching record |
Overview
The Metadata API retrieves cluster topology, broker information, and topic/partition metadata.
Version History
| Version |
Kafka |
Key Changes |
| 0 |
0.8.0 |
Initial version |
| 1 |
0.10.0 |
Rack ID support |
| 2 |
0.10.1 |
Cluster ID |
| 3 |
0.10.2 |
Throttle time |
| 4 |
0.11.0 |
Topic-level errors |
| 5 |
1.0.0 |
Offline replicas |
| 6 |
1.1.0 |
Response before throttling |
| 7 |
2.0.0 |
Leader epoch |
| 8 |
2.1.0 |
Allow topic auto-create control |
| 9 |
2.4.0 |
Flexible versions |
| 10 |
2.8.0 |
Topic ID field (not implemented) |
| 11 |
3.0.0 |
Cluster authorized ops deprecated |
| 12 |
3.4.0 |
Topic ID supported |
| 13 |
4.0.0 |
Top-level error code |
Request Schema
MetadataRequest =>
topics: [TopicRequest]
allow_auto_topic_creation: BOOLEAN
include_cluster_authorized_operations: BOOLEAN
include_topic_authorized_operations: BOOLEAN
TopicRequest =>
topic_id: UUID
name: NULLABLE_STRING
| Field |
Type |
Description |
topics |
ARRAY |
Topics to fetch (null for all topics) |
allow_auto_topic_creation |
BOOLEAN |
Allow auto-creation of missing topics |
include_cluster_authorized_operations |
BOOLEAN |
Include cluster ACL info (v8-10) |
include_topic_authorized_operations |
BOOLEAN |
Include topic ACL info |
Topic IDs are supported in v12+; v10-11 include the field but brokers do not implement it.
Response Schema
MetadataResponse =>
throttle_time_ms: INT32
brokers: [BrokerMetadata]
cluster_id: NULLABLE_STRING
controller_id: INT32
topics: [TopicMetadata]
cluster_authorized_operations: INT32
error_code: INT16
BrokerMetadata =>
node_id: INT32
host: STRING
port: INT32
rack: NULLABLE_STRING
TopicMetadata =>
error_code: INT16
name: STRING
topic_id: UUID
is_internal: BOOLEAN
partitions: [PartitionMetadata]
topic_authorized_operations: INT32
PartitionMetadata =>
error_code: INT16
partition_index: INT32
leader_id: INT32
leader_epoch: INT32
replica_nodes: [INT32]
isr_nodes: [INT32]
offline_replicas: [INT32]
| Field |
Type |
Description |
controller_id |
INT32 |
Current controller broker ID |
cluster_id |
NULLABLE_STRING |
Cluster identifier |
leader_id |
INT32 |
Partition leader broker ID (-1 if none) |
replica_nodes |
ARRAY |
All replica broker IDs |
isr_nodes |
ARRAY |
In-sync replica broker IDs |
offline_replicas |
ARRAY |
Offline replica broker IDs |
Behavioral Contract
| Aspect |
Guarantee |
| Completeness |
All brokers the client may need to contact |
| Freshness |
May be slightly stale after topology changes |
| Auto-creation |
May create topics if enabled and requested |
| Leader info |
Leader may have changed since response |
Metadata Staleness
Metadata responses may be stale. Clients must handle NOT_LEADER_OR_FOLLOWER errors by refreshing metadata and retrying.
Client Caching
| Behavior |
Recommendation |
| Cache metadata per cluster |
should |
| Refresh on NOT_LEADER errors |
must |
| Periodic refresh interval |
metadata.max.age.ms |
ApiVersions API (Key 18)
Overview
The ApiVersions API queries the broker for supported API versions. It is the first API called during connection setup.
Version History
| Version |
Kafka |
Key Changes |
| 0 |
0.10.0 |
Initial version |
| 1 |
0.10.1 |
Throttle time |
| 2 |
2.1.0 |
Response before throttling |
| 3 |
2.4.0 |
Flexible versions |
| 4 |
4.0.0 |
SupportedFeatures min version fix |
Request Schema
ApiVersionsRequest =>
client_software_name: STRING
client_software_version: STRING
| Field |
Type |
Description |
client_software_name |
STRING |
Client library name (v3+) |
client_software_version |
STRING |
Client library version (v3+) |
Response Schema
ApiVersionsResponse =>
error_code: INT16
api_versions: [ApiVersion]
throttle_time_ms: INT32
supported_features: [SupportedFeature]
finalized_features_epoch: INT64
finalized_features: [FinalizedFeature]
zk_migration_ready: BOOLEAN
ApiVersion =>
api_key: INT16
min_version: INT16
max_version: INT16
| Field |
Type |
Description |
api_key |
INT16 |
API identifier |
min_version |
INT16 |
Minimum supported version |
max_version |
INT16 |
Maximum supported version |
Special Handling
| Behavior |
Description |
| Pre-authentication |
Broker must respond before SASL authentication |
| Version tolerance |
Broker should accept any valid request version |
| Error fallback |
On UNSUPPORTED_VERSION, client may try older version |
Behavioral Contract
| Aspect |
Guarantee |
| Availability |
Must be available before authentication |
| Accuracy |
Version ranges must reflect actual capabilities |
| Completeness |
Must include all supported APIs |
| Consistency |
Should not change during connection lifetime |
Complete API Key Table
All Kafka Protocol APIs
| Key |
Name |
Category |
First Version |
| 0 |
Produce |
Core |
0.8.0 |
| 1 |
Fetch |
Core |
0.8.0 |
| 2 |
ListOffsets |
Core |
0.8.0 |
| 3 |
Metadata |
Core |
0.8.0 |
| 4 |
LeaderAndIsr |
Controller |
0.8.0 |
| 5 |
StopReplica |
Controller |
0.8.0 |
| 6 |
UpdateMetadata |
Controller |
0.8.0 |
| 7 |
ControlledShutdown |
Controller |
0.8.0 |
| 8 |
OffsetCommit |
Consumer |
0.8.1 |
| 9 |
OffsetFetch |
Consumer |
0.8.1 |
| 10 |
FindCoordinator |
Consumer |
0.8.2 |
| 11 |
JoinGroup |
Consumer |
0.9.0 |
| 12 |
Heartbeat |
Consumer |
0.9.0 |
| 13 |
LeaveGroup |
Consumer |
0.9.0 |
| 14 |
SyncGroup |
Consumer |
0.9.0 |
| 15 |
DescribeGroups |
Consumer |
0.9.0 |
| 16 |
ListGroups |
Consumer |
0.9.0 |
| 17 |
SaslHandshake |
Auth |
0.10.0 |
| 18 |
ApiVersions |
Core |
0.10.0 |
| 19 |
CreateTopics |
Admin |
0.10.1 |
| 20 |
DeleteTopics |
Admin |
0.10.1 |
| 21 |
DeleteRecords |
Admin |
0.11.0 |
| 22 |
InitProducerId |
Transaction |
0.11.0 |
| 23 |
OffsetForLeaderEpoch |
Replication |
0.11.0 |
| 24 |
AddPartitionsToTxn |
Transaction |
0.11.0 |
| 25 |
AddOffsetsToTxn |
Transaction |
0.11.0 |
| 26 |
EndTxn |
Transaction |
0.11.0 |
| 27 |
WriteTxnMarkers |
Transaction |
0.11.0 |
| 28 |
TxnOffsetCommit |
Transaction |
0.11.0 |
| 29 |
DescribeAcls |
Admin |
0.11.0 |
| 30 |
CreateAcls |
Admin |
0.11.0 |
| 31 |
DeleteAcls |
Admin |
0.11.0 |
| 32 |
DescribeConfigs |
Admin |
0.11.0 |
| 33 |
AlterConfigs |
Admin |
0.11.0 |
| 34 |
AlterReplicaLogDirs |
Admin |
0.11.0 |
| 35 |
DescribeLogDirs |
Admin |
0.11.0 |
| 36 |
SaslAuthenticate |
Auth |
1.0.0 |
| 37 |
CreatePartitions |
Admin |
1.0.0 |
| 38 |
CreateDelegationToken |
Auth |
1.1.0 |
| 39 |
RenewDelegationToken |
Auth |
1.1.0 |
| 40 |
ExpireDelegationToken |
Auth |
1.1.0 |
| 41 |
DescribeDelegationToken |
Auth |
1.1.0 |
| 42 |
DeleteGroups |
Consumer |
1.1.0 |
| 43 |
ElectLeaders |
Admin |
2.2.0 |
| 44 |
IncrementalAlterConfigs |
Admin |
2.3.0 |
| 45 |
AlterPartitionReassignments |
Admin |
2.4.0 |
| 46 |
ListPartitionReassignments |
Admin |
2.4.0 |
| 47 |
OffsetDelete |
Consumer |
0.11.0 |
| 48 |
DescribeClientQuotas |
Admin |
2.6.0 |
| 49 |
AlterClientQuotas |
Admin |
2.6.0 |
| 50 |
DescribeUserScramCredentials |
Auth |
2.7.0 |
| 51 |
AlterUserScramCredentials |
Auth |
2.7.0 |
| 52 |
Vote |
KRaft |
2.7.0 |
| 53 |
BeginQuorumEpoch |
KRaft |
2.7.0 |
| 54 |
EndQuorumEpoch |
KRaft |
2.7.0 |
| 55 |
DescribeQuorum |
KRaft |
2.7.0 |
| 56 |
AlterPartition |
Controller |
2.7.0 |
| 57 |
UpdateFeatures |
Admin |
2.7.0 |
| 58 |
Envelope |
KRaft |
2.7.0 |
| 59 |
FetchSnapshot |
KRaft |
3.0.0 |
| 60 |
DescribeCluster |
Admin |
3.0.0 |
| 61 |
DescribeProducers |
Admin |
3.0.0 |
| 62 |
BrokerRegistration |
KRaft |
3.0.0 |
| 63 |
BrokerHeartbeat |
KRaft |
3.0.0 |
| 64 |
UnregisterBroker |
KRaft |
3.0.0 |
| 65 |
DescribeTransactions |
Transaction |
3.0.0 |
| 66 |
ListTransactions |
Transaction |
3.0.0 |
| 67 |
AllocateProducerIds |
KRaft |
3.0.0 |
| 68 |
ConsumerGroupHeartbeat |
Consumer |
3.5.0 |
| 69 |
ConsumerGroupDescribe |
Consumer |
3.5.0 |
| 70 |
ControllerRegistration |
KRaft |
3.5.0 |
| 71 |
GetTelemetrySubscriptions |
Telemetry |
3.5.0 |
| 72 |
PushTelemetry |
Telemetry |
3.5.0 |
| 73 |
AssignReplicasToDirs |
KRaft |
3.6.0 |
| 74 |
ListConfigResources |
Telemetry |
3.6.0 |
| 75 |
DescribeTopicPartitions |
Admin |
3.7.0 |
| 76 |
ShareGroupHeartbeat |
Share |
4.0.0 |
| 77 |
ShareGroupDescribe |
Share |
4.0.0 |
| 78 |
ShareFetch |
Share |
4.0.0 |
| 79 |
ShareAcknowledge |
Share |
4.0.0 |
| 80 |
AddRaftVoter |
KRaft |
4.0.0 |
| 81 |
RemoveRaftVoter |
KRaft |
4.0.0 |
| 82 |
UpdateRaftVoter |
KRaft |
4.0.0 |
| 83 |
InitializeShareGroupState |
Share |
4.0.0 |
| 84 |
ReadShareGroupState |
Share |
4.0.0 |
| 85 |
WriteShareGroupState |
Share |
4.0.0 |
| 86 |
DeleteShareGroupState |
Share |
4.0.0 |
| 87 |
ReadShareGroupStateSummary |
Share |
4.0.0 |
| 88 |
StreamsGroupHeartbeat |
Streams |
4.0.0 |
| 89 |
StreamsGroupDescribe |
Streams |
4.0.0 |
| 90 |
DescribeShareGroupOffsets |
Share |
4.0.0 |
| 91 |
AlterShareGroupOffsets |
Share |
4.0.0 |
| 92 |
DeleteShareGroupOffsets |
Share |
4.0.0 |