Bluetooth GATT Descriptor Reference

Characteristic Aggregate Format (0x2905)

org.bluetooth.descriptor.gatt.characteristic_aggregate_format

Only one Characteristic Aggregate Format descriptor exists in a characteristic definition. This descriptor consists of a list of Attribute Handles pointing to Characteristic Presentation Format declarations. This descriptor is read only and does not require authentication or authorization. The list of Attribute Handles is the concatenation of multiple 16-bit Attribute Handle values into a single Attribute Value. If more than one Characteristic Presentation Format declarations exist, then there is one Characteristic Aggregate Format declaration. However, a Characteristic Aggregate Format descriptor can be present even if there aren't any Presentation Format descriptors in the characteristic definition. The order of the Attribute Handles in the list is significant.

Quick Summary

Payload length is 2 bytes. This page is generated from official GATT XML and presented as implementation-ready guidance.

At a Glance

Key reference details for BLE implementation, interoperability testing, and AI-assisted troubleshooting.

Property	Value
Name	Characteristic Aggregate Format
UUID	0x2905
Type	org.bluetooth.descriptor.gatt.characteristic_aggregate_format
XML Root	Descriptor
Source File	org.bluetooth.descriptor.gatt.characteristic_aggregate_format.xml
Field Count	1

Field Specification

Parsed field definitions from the source XML value structure.

Field	Requirement	Format	Unit	Exponent	Notes
List of Handles	Mandatory	uint16	-	-	-

Byte Layout and Decode

Payload length is 2 bytes.

function decodePayload(dataView, offset = 0) {
  const list_of_handles = dataView.getUint16(offset + 0, true);
  return { list_of_handles };
}

Use Cases and Integration Notes

Descriptor Validation

Verify descriptor presence and format during integration and interoperability testing.

Client Configuration

Use descriptor semantics to configure notifications, indications, or presentation metadata.

Debug Diagnostics

Capture descriptor values alongside characteristic data for deeper BLE troubleshooting.

Implementation Checklist

Read descriptor metadata after characteristic discovery to confirm behavior contracts.
Respect descriptor read/write requirements before ATT operations.
Document descriptor values in exported BLE session logs for reproducibility.
Keep descriptor handling aligned with Bluetooth SIG format definitions.

FAQ

What is Characteristic Aggregate Format in Bluetooth GATT?

Characteristic Aggregate Format is defined as a Bluetooth GATT descriptor entry with type org.bluetooth.descriptor.gatt.characteristic_aggregate_format and UUID 0x2905.

What UUID identifies Characteristic Aggregate Format?

The UUID for Characteristic Aggregate Format is 0x2905.

How should I parse Characteristic Aggregate Format?