// glossary
This is the reference page for terms from the Reticulum and LXMF documentation. Read What is Reticulum? first for the overview, and use this page whenever you need a precise definition.
| Identity | The cryptographic basis of a Reticulum participant, service or device. An identity is a 64-byte private keyset: 32 bytes for X25519 key agreement and 32 bytes for an Ed25519 signing seed. Treat it like an SSH key. Whoever holds the private key can act as that identity. |
| Destination | An addressable endpoint created by an application. It combines an identity, an application name and one or more aspects (such as lxmf.delivery). Reticulum has four destination types: Single, Group, Plain and Link. |
| Destination Hash | The 16-byte truncated SHA-256 value that Reticulum routes towards. Shown in interfaces as 32 hex characters, for example 4faf1b2e0a077e6a9d92fa051f256038. Reticulum does not route on IP addresses, domain names, usernames or phone numbers. |
| Name Hash | The 10-byte hash of an application destination name such as lxmf.delivery. For Single destinations the final destination hash also includes the identity hash, which lets two users each have an lxmf.delivery destination without sharing the same address. |
| Ratchet | A rotating X25519 key advertised through announces. It provides forward secrecy for link-less Single destination packets. Defaults: 512 generated ratchets, rotation no more often than every 1800 seconds, received ratchets expire after about 30 days. |
| Reticulum Instance | A running Reticulum stack on a device or process. It manages interfaces, keeps local path state and sends/receives traffic for local applications. |
| Transport Node | A Reticulum instance with enable_transport = yes. It forwards packets for other nodes and makes multi-hop reachability possible. Always-on machines, gateways and infrastructure nodes are good candidates. |
| Announce | A signed packet that tells the mesh that a destination exists and how it can be reached. Announces contain public key material, optional application data and an optional ratchet key. Transport nodes use announces to fill path tables. |
| Path | A route to a destination, stored locally as next hop, interface and hop count. A transport node only knows the next step, not the whole mesh. |
| Path Request | A request to the network to find or refresh a route to a destination hash. |
| Hop | A forwarding step through a transport node. The default maximum announce depth is 128 hops. |
| Mesh | The collection of Reticulum nodes reachable through one or more compatible interfaces and transport nodes. A mesh can span mixed media: LoRa, LAN, TCP, I2P, BLE, serial and other carriers. |
| Interface | A driver that lets Reticulum send and receive bytes over a specific medium. Examples: TCP, UDP, AutoInterface, RNode LoRa, serial, KISS, I2P, Backbone, Bluetooth LE. |
| AutoInterface | Zero-configuration LAN discovery through IPv6 multicast. Defaults: UDP port 29716 for discovery, port 42671 for data. It only works if the local network allows multicast. |
| RNode | A class of LoRa transceivers that speak Reticulum-friendly framing over USB serial, Android USB-OTG, Bluetooth LE or a TCP bridge. This lets Reticulum work over radio, without a mobile network or internet. |
| KISS | A simple framing protocol from packet radio. Reticulum's KISS interfaces work with TNCs, modems and compatible radio devices that offer KISS over serial or TCP. |
| Backbone | A TCP interface for heavy traffic over WAN links between Reticulum nodes. Meant for servers and infrastructure. |
| IFAC | Interface Access Codes. Signs packets with material derived from an interface name or pre-shared passphrase. Receivers without matching IFAC settings drop those packets. IFAC segments a carrier, it does not replace end-to-end encryption. |
| Announce Cap | The share of an interface's bandwidth that may be spent on announces and maintenance traffic. Default: 2%, so routing updates never permanently crowd out payload traffic on slow links. |
| Single Destination | The most commonly used destination type. Bound to an identity, reachable over multiple hops. Packets are encrypted for the holder of that identity's private key, or for the current ratchet key when one is known. |
| Plain Destination | A direct-only, unencrypted destination type for local public broadcast or discovery. It is not transported over multiple hops. |
| Group Destination | A direct-only destination encrypted with a pre-shared symmetric key. Anyone with the group key can read packets for that destination. |
| Link | An encrypted point-to-point session between two destinations. It can span multiple hops, uses ephemeral key exchange and is the basis for reliable channels, request/response and larger transfers. |
| Resource | A reliable transfer over a link for payloads larger than a single packet. It handles chunking, sequencing, verification, retransmission and reassembly. |
| MTU / MDU | Reticulum's default network MTU is 500 bytes. Plain packet MDU: 464 bytes. Encrypted Single packet payload: 383 bytes. Link packet MDU: 431 bytes. |
| Forward Secrecy | The property that compromising a long-term identity key does not retroactively decrypt old traffic later. Reticulum achieves this through ephemeral link key exchange and, for link-less packets, through destination ratchets. |
| End-to-End Encryption | Encryption applied by the sender and only removed by the intended receiver. Transport nodes forward sealed bytes; they have no plaintext access. |
| LXMF | Lightweight Extensible Message Format. The messaging layer used by Ratspeak, Sideband, NomadNet and other Reticulum applications. It defines message serialization, sender signatures, delivery methods, propagation, stamps and tickets. |
| Direct Delivery | LXMF opens a Reticulum link to the receiver and delivers the message over that encrypted session. The preferred method when the receiver is reachable. |
| Opportunistic Delivery | LXMF sends a small message as a single encrypted Reticulum packet without building a link. Practical LXMF content limit: about 295 bytes. Fast and cheap, but without link-level acknowledgement. |
| Propagated Delivery | LXMF hands the encrypted message blob to a propagation node that stores it until the receiver connects and collects the waiting messages. |
| Propagation Node | An LXMF daemon (such as lxmd or lxmd-rs) that stores messages for offline receivers. It is a delivery helper, not a trust anchor: message content stays encrypted for the receiver. |
| Stamp | A proof-of-work value attached to an LXMF message as spam resistance. Unknown senders may have to do CPU work to produce a stamp that meets the receiver's advertised cost. |
| Ticket | A per-sender token that lets a trusted correspondent skip stamp work for future messages. |