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FreeDMR 2 Glossary
This glossary defines FreeDMR 2 terms. Legacy terms such as SYSTEM, MASTER, BRIDGES, and # reflector names describe current implementation details or compatibility views, not the primary FreeDMR 2 model.
Access layer: The part of FreeDMR that accepts client/repeater protocols such as HBP. It owns login, authentication, options, keepalive, access sessions, RF-facing slots, and RF-visible TG presentation.
Access session: A live connection-like relationship between FreeDMR and a client/repeater. It is identified by client DMR ID and transport/session metadata, not by a configured listener stanza.
Listener: A UDP socket/service endpoint that accepts one or more access sessions. A configured MASTER is a legacy listener-like concept, not the client identity.
Client/repeater: An HBP hotspot, repeater, gateway, bridge, or future access-side system connected to FreeDMR.
Client DMR ID: The DMR ID used by a client/repeater access session. Future routing should key primarily on client DMR ID, slot, and RF-visible TG.
RF-visible TG: The talkgroup number seen by the RF terminal or access-side device. In dial-a-TG this may be TG9 while the network conference TG is different.
Conference TG: The FreeDMR network talkgroup identity. Conceptually this is the conference bridge to which clients subscribe.
Subscription: Membership of a client slot/RF TG presentation in a conference TG.
Static subscription: A subscription created by configuration or policy and normally present for the session.
Dial-a-TG subscription: A subscription created by dial-a-TG control. It maps an RF-visible TG, traditionally TG9, to a selected conference TG.
Default reflector: A configured or client-requested default dial-a-TG style subscription for a session. Empty string, integer 0, or boolean false means no default reflector.
Stream: A voice call flow identified by stream metadata. AMBE voice is a stream; DMR data packets are packet-oriented and should not be treated as AMBE streams.
Source server: The server that originated or advertised the packet into the mesh, according to the FBP/OBP protocol version in use.
Source repeater: The access-side repeater/client identity carried when the protocol version supports it.
Mesh peer: Another FreeDMR/OpenBridge/FBP peer server connected through the mesh layer.
Server ID: A FreeDMR server identity. Server IDs are treated separately from client DMR IDs.
Server sub-ID: A subordinate server identity authorized under a server/sysop identity, for example backend or fault-tolerant deployments.
Bridge-control message: An out-of-band FBP/OBP control message, such as source quench or STUN.
Packet plane: The delay-sensitive path that receives, parses, routes, mutates where necessary, and sends DMR packets.
Control plane: Authenticated configuration, API, bridge-control, admission, and policy operations.
Reporting plane: Observational events and state export for dashboards, logs, lastheard, monitoring, and operators.
Compatibility/export state: A derived view that presents old FreeDMR/HBLink/dashboard shapes to consumers. It is not authoritative state.
HBP: Homebrew Protocol, used by many hotspots/repeaters on the access side.
OBP: OpenBridge Protocol version 1. It remains important as an open interop path where intentionally configured.
FBP: FreeDMR Bridge Protocol. Any OpenBridge-derived peer protocol version higher than 1 is termed FBP for FreeDMR clarity.
DATA-GATEWAY: A historical/early expression of a data-oriented FBP link. FreeDMR 2 should preserve data forwarding without making the core a GPS/SMS application processor.
Source quench / BCSQ: A bridge-control hint asking a peer to suppress a stream/TG toward us. It is optional and per stream/TG.
STUN / BCST: A broader bridge-control gate intended to stop all FBP traffic from a peer under the current conceptual model.
OVCM: Open Voice Channel Mode. ETSI service option bit 0x04 when explicitly used. HBLink legacy 0x20 is compatibility history, not standards-clean OVCM.
Synthetic LC: A generated Link Control value used when FreeDMR has to create fallback LC information.
Real inbound LC: LC decoded from received traffic. It should be preserved unchanged unless FreeDMR deliberately rewrites it.