Glossary

A quick lookup for terms used in the device API. Follow the links for wire formats, supported operations and message-specific behavior.

Messages and fields

Term	Description
Message / frame	One unit of communication encoded using the Lightbug protocol. “Frame” refers to its encoded form on the wire.
Message type (MT)	The number identifying a message's purpose and payload format, such as MT35 for Device IDs. It is not an individual Message ID.
Prefix	Optional bytes before a message to help identify it in a byte stream: `0x4c, 0x42` (`LB` in ASCII).
Header	Shared metadata fields such as Message ID, Method and Status. The outer version, length and message type are separate from header data in the message structure.
Payload	The message-specific data fields. A field named “Payload” may itself contain application bytes; its meaning is defined on the relevant message page.
Header field ID	A `uint8` identifier selecting a shared header field, not the data type of its value. Also called a header field type.
Payload field ID	A `uint8` identifier selecting a field within a message's payload. Its meaning and value type depend on the message type. Also called a payload field type.
bBytes	A byte array that represents a length and that amount of data in bytes. The length prefix is a `uint8` (1 byte) for data type IDs 0–127, or a little-endian `uint16` (2 bytes) for data type IDs 128–255. A bByte entry for a sub-128 field might be `3 9 9 9`, where `3` is the length, and `9 9 9` is the data. A bByte entry for a field with ID 128 or greater might be `3 0 9 9 9`, where `3` is the length, and `9 9 9` is the data. See structure.
Little-endian	Byte order with the least-significant byte first, used for protocol integers.

Identifiers and versions

Term	Description
Message ID	Identifies an individual message for tracking or correlating a reply; distinct from Message Type and Device ID.
Response to	Identifies the request or subscription a message responds to. See reply correlation.
Client ID	Identifies the client sending a message. Its interpretation depends on the context; Lightbug cloud services associate it with a Device ID.
Device ID	The Lightbug device identifier used by the cloud API, distinct from the modem's IMEI, the SIM's ICCID and the device serial number.
Subscription ID	Identifies a subscription within a message type. Omitting it addresses the default subscription, ID `0`.
Protocol version	The version of the outer message encoding, currently V3. It is independent of Message Version and firmware version.
Message Version	Selects or identifies a message-specific payload format where supported. Supported values and defaults are defined by each message.
Firmware version	Identifies the software running on a device. Its encoding depends on the target and is separate from protocol and message-format versions.

Requests and updates

Term	Description
Method	The requested operation, such as GET, SET, SUBSCRIBE or UNSUBSCRIBE. Supported methods and omission rules depend on the message.
ACK / typed response	An ACK (MT5) acknowledges another message; a typed response carries the operation's documented reply payload. Neither a reply nor an ACK necessarily means the operation is complete.
Subscription / publication	A subscription requests later updates of a message type. A publication is an update, distinct from the subscription's control reply.
Status	A shared header reporting the reply's outcome or progress. It is separate from any message-specific payload field named Status.

Term	Description
GNSS / GPS	GNSS is satellite-based positioning; GPS is one of its satellite constellations.
RTK / correction data / RTCM	RTK improves GNSS positioning using correction data, commonly carried in RTCM formats.
Toit	A programming language for IoT devices, supported by the Lightbug SDK.
ESP32	A microcontroller with WiFi and Bluetooth, used in some Lightbug devices.