# Glossary URL: /reference/glossary The terms these docs and the Foxborne console use, from anchor to write-once, each defined in one or two sentences with a link to the page that explains it in full. Terms are in alphabetical order. Each one has a stable anchor you can link to, such as `/reference/glossary#order-unknown`. What places a source's clock on UTC: GPS time for the flight log, chrony for the companion journal, NTP for the ground receiver. A source without one stays on its own clock, and Foxborne makes no before or after claim between it and anchored sources. The link between audit log entries: each entry carries the hash of the one before it, so a missing or altered entry breaks the chain. **Verify chain** recomputes each hash from its entry and the hash before it. The identifier of one boot of the companion computer: `_BOOT_ID` in the journal and `boot_id` in collector records. Process samples that share the journal's boot ID share its clock. How far a source's time can be off once anchored, written ±N, such as ±40 ms for a GPS-anchored flight log. A receipt adds link latency on the early side only. A local admin account for when the identity provider is down. It requires a hardware security key, and each break-glass sign-in is audited and raises an alert in your SIEM. The incident's report exported on marked pages, as a PDF case file with CUI markings, hashed with a SHA-256 manifest. Another engineer can check every excerpt against the originals without access to your deployment. The service that keeps the companion computer's clock on UTC. Foxborne trusts the journal's wall time only while chrony reports a synchronized source. A group of sources that share one clock, so their events are always in order against each other. The companion journal and process samples share one; the flight log and the ground receiver each have their own. The optional Foxborne service on a vehicle's companion computer. It reads allowlisted journal units and processes, spools offline, uploads over mutual TLS and never sends MAVLink to the flight controller. The sum of two sources' bounds, plus link latency when one of them is a receipt. Two events closer than it cannot be put in order: the flight log's ±40 ms and the journal's ±6 ms combine to ±46 ms. The systemd journal of a vehicle's companion computer, exported with `journalctl -o json` or uploaded by the collector. Each entry carries wall time, monotonic time and the boot ID. The evidence level for events that line up inside a known error bound. In INC-0142, the next heartbeat was due 0.76 s after the router stopped. Controlled unclassified information. Under a CUI marking, reports and case files carry the banner on every page and the designation indicator on the first. The block on the first page of every report and case file that says who controls the CUI. It gives the controlling organization, the office, the CUI category, the dissemination control and a point of contact. Setting a finding aside, with a reason that is required. The raw evidence does not change, and the audit log keeps the dismissal and its reason. A gap that the flight log itself marks as dropped data. `log_dropout` flags dropouts of 50 ms or longer. The clock state of a run with no anchor to UTC, such as an indoor hover with no GPS fix. Times read from log start, and nothing on the run is shown as wall-clock time. The side panel on an incident's **Reconstruction** tab that opens when you select an event. It shows the event's time and bound, source file with its SHA-256, original record and order against nearby events. How directly the sources support a statement: observed, correlated, hypothesis or unknown. The console and reports draw each level with its own shape. A source record quoted byte for byte in a report, with its file's SHA-256 and its location, such as a line or row. The CUI registry's category marking for export-controlled information. Evidence marked EXPT opens only for users whose identity provider asserts US person status. PX4's automatic response to a failure condition, such as the action `NAV_DLL_ACT` selects once `COM_DL_LOSS_T` runs out. `failsafe_entered` reports each failsafe with its cause from `failsafe_flags` . A rule's result: what it observed, with the rule ID, version and threshold that produced it and the events it read. A report's first section, also called Finding, is the engineer's own paragraph. The PX4 ULog ( `.ulg` ) from the flight controller's SD card. Its clock counts microseconds from boot, and GPS time in `sensor_gps` anchors it to UTC. The record of MAVLink messages the receiver at range control heard, one receiver JSONL line per message. The receiver stamps each line on arrival with its own clock. The MAVLink message with ID 0, which each system sends at a steady rate, 1 Hz on typical radio links. `telemetry_gap` flags more than 3 s between heartbeats at the ground receiver. The evidence level for an explanation that still needs a check. A report's **Next check** names one test or measurement that would confirm or refute it. The steps Foxborne ran on a run's files, with their timings: validate, hash, parse, align clocks and run the rules. The same files and parser versions give the same event IDs. One failure under investigation, opened on a window of a run, with the evidence behind every claim and an account of what is still unknown. The stretch of a run an incident covers, such as 14:31:53 to 14:32:16 in INC-0142. **Fit incident** returns the timeline to it. The time a message takes from the vehicle to the ground receiver. Foxborne measures it per run and extends a receipt's bound toward earlier times only. A hold that keeps a run from deletion, whatever the retention policy. Shortening retention does not delete anything on hold. The marker the collector writes where it dropped samples after its spool budget filled, so the gap shows on the timeline instead of passing unnoticed. An offset an engineer applies to an unaligned companion clock, from two events that happened at the same moment on both clocks. It carries its own, wider bound, and reports list it under Limitations. Military Grid Reference System, the position format Foxborne uses on screen and in reports. Foxborne shows it at 10 m precision, such as `13R FP 7640 8765` . Network Time Protocol. It keeps the ground receiver's clock on UTC, to ±15 ms in the example dataset. The evidence level for a value, event or log line captured directly. Rule wording starts with Observed, except for `clock_uncertain` , which starts with Warning. A question recorded on a report. It travels with the case file until someone resolves it. The verdict for two events on different clocks whose error intervals overlap, so either could have come first. In INC-0142, the last `obstacle_distance` sample and the kernel kill are 39 ms apart inside a 46 ms combined bound. The error above which Foxborne makes no before or after claim between two sources, whatever the times say. It is 2.0 s by default, and admins can set 0.5, 1.0 or 5.0 s instead. An imported file exactly as it arrived, hashed with SHA-256 on arrival and stored write-once. Each excerpt in a report traces back to one. The parser and version that read a file, such as `ulog 0.9.2` , shown for each file on the run page. Parsing the same file with the same parser version gives the same event IDs. The collector's per-process records of CPU, resident memory and restart count, in collector JSONL. They share the companion journal's clock through the boot ID. The status of a file that claims a supported format but cannot be read in full, such as a truncated flight log. Nothing from it is shown as complete. The timeline lane that draws one tick per message the ground receiver recorded, so a receive gap shows as empty space. The MAVLink receiver at range control, which listens to telemetry on the ground and records every receipt with its own clock. Removing sensitive content: patterns the collector replaces with `[redacted]` on the vehicle before upload, and coordinates removed from exported reports unless the exporter keeps them. The status of a file Foxborne does not read, such as an unsupported format, an encrypted flight log or a file above the size limit. The reason appears with the file. An incident's hand-off document: the engineer's finding, the sequence, evidence excerpts with hashes, limitations, open questions and the next check, under your marking. A deterministic detection with a fixed threshold, scope and wording. Each result records the rule version, its threshold and the events it read. The version a rule carries, such as `telemetry_gap 1.3` . Saving a changed threshold creates the next minor version, and findings keep the version that produced them. One flight or bench session and the files that record it, such as its flight log, companion journal, process samples and ground receive log. Software bill of materials. Each Foxborne release carries one, SPDX 2.3 with 412 components for 1.4.2, and the installer checks it along with the signature. System for Cross-domain Identity Management. With it on, your identity provider provisions Foxborne users and groups, and removing someone there removes them here within five minutes. The events a report walks through in time order, each with its time, bound, evidence level and a reference to its source. The hash Foxborne computes for every original on arrival. Reports quote each excerpt with its file's SHA-256, so anyone holding the original can check it. A Foxborne update as an `.fxb` file that your administrator brings in. Foxborne checks its signature against the Foxborne release key before anything installs. One kind of evidence in a run, such as the flight log, companion journal, process samples or ground receive log. On the **Sources** page, a source is also a read-only connection that Foxborne reads files from. The collector's store on the vehicle while it has no uplink. Samples leave it only once their upload is acknowledged, and low-priority samples go first when the budget fills. A vehicle's MAVLink system ID, `sysid` in receive records. Foxborne matches flight logs to vehicles by it. A MAVLink message in which a system reports its UTC time and its time since boot. Collector 0.8.1 records `SYSTEM_TIME` pairs, which give companion evidence a shared anchor with the flight log. The notice on the sign-in page that everyone acknowledges before each session. Admins set its text in **Settings** , and each change is audited. The uORB topic each PX4 MAVLink instance publishes about its link. Its `heartbeat_type_gcs` flag turns false once 2.5 s pass without a ground station heartbeat ( `HEARTBEAT_TIMEOUT_US` ). PX4's binary flight log format, with the file extension `.ulg` . Foxborne recognizes it by its first bytes, `55 4C 6F 67 01 12 35` . The evidence level for a question the evidence cannot decide, because sources are missing, partial or disagree on time. A message stream on PX4's internal publish and subscribe bus, such as `vehicle_status` or `sensor_gps` . The flight log records selected topics, and `topic_stall` flags one that stops updating. A status your identity provider asserts in the `usPerson` SAML attribute. It gates evidence marked EXPT. A platform Foxborne has evidence for, identified by its vehicle ID and MAVLink system ID. Its page shows its failsafe parameters and the changes between runs. How Foxborne stores originals: written once and never rewritten. Reviewers annotate beside the evidence, never on top of it.