# invariant > Every PAG keyword record, with what grounds it and how it is checked. Page: Ontology · Grammar Canonical: https://banes-lab.com/ontology/grammar#pag-keywords-invariant Listed in [Ontology · Grammar](https://banes-lab.com/api/pages/ontology/grammar.md), after [report](https://banes-lab.com/ontology/grammar/pag-keywords-report.md) and before [node](https://banes-lab.com/ontology/grammar/pag-keywords-node.md). Every PAG keyword record, with what grounds it and how it is checked. ### INVARIANT Details Meaning The record head · a property the topology relies on, with its set, its parties and its objector Example INVARIANT : over: binds: objector: Grounds [substrate-node:invariant](https://banes-lab.com/records/reasoning/substrate-node-invariant.md), [invariant:epi-reachable-check](https://banes-lab.com/records/reasoning/invariant-epi-reachable-check.md) How it is checked Checked by a structured-document validator that parses each document against the grammar and reports every defect by its shape Population Every agent and template document the validator walks, and every occurrence of the keyword in them Freshness A verdict stands until the grammar data or a document that uses the keyword changes Refusal The validation stage fails the gate on any defect code, so a document with a malformed keyword does not ship Observation None, because a keyword is static text in a document, and nothing observes it while a run executes Evidence Watched to fire and to accept: a suite plants a retired head in a real template and validates every agent and template on disk clean Authoritative side The grammar data, which every keyword in a document conforms to Depends on Not answered Shape it refuses Not answered ### PROPERTY Details Meaning The property, in a form that could be false Example INVARIANT one-writer: a record has exactly one writer ... Grounds [substrate-node:invariant](https://banes-lab.com/records/reasoning/substrate-node-invariant.md) How it is checked Checked by a structured-document validator that parses each document against the grammar and reports every defect by its shape Population Every agent and template document the validator walks, and every occurrence of the keyword in them Freshness A verdict stands until the grammar data or a document that uses the keyword changes Refusal The validation stage fails the gate on any defect code, so a document with a malformed keyword does not ship Observation None, because a keyword is static text in a document, and nothing observes it while a run executes Evidence Watched to fire and to accept: a suite plants a retired head in a real template and validates every agent and template on disk clean Authoritative side The grammar data, which every keyword in a document conforms to Depends on Not answered Shape it refuses Not answered ### OVER Details Meaning The set the property quantifies over Example over: every record on the surface Grounds [node:ver-population](https://banes-lab.com/records/reasoning/node-ver-population.md) How it is checked Checked by a structured-document validator that parses each document against the grammar and reports every defect by its shape Population Every agent and template document the validator walks, and every occurrence of the keyword in them Freshness A verdict stands until the grammar data or a document that uses the keyword changes Refusal The validation stage fails the gate on any defect code, so a document with a malformed keyword does not ship Observation None, because a keyword is static text in a document, and nothing observes it while a run executes Evidence Watched to fire and to accept: a suite plants a retired head in a real template and validates every agent and template on disk clean Authoritative side The grammar data, which every keyword in a document conforms to Depends on Not answered Shape it refuses Not answered ### BINDS Details Meaning The parties the property constrains · who must receive it Example binds: every party writing there Grounds [substrate-node:constraint](https://banes-lab.com/records/reasoning/substrate-node-constraint.md) How it is checked Checked by a structured-document validator that parses each document against the grammar and reports every defect by its shape Population Every agent and template document the validator walks, and every occurrence of the keyword in them Freshness A verdict stands until the grammar data or a document that uses the keyword changes Refusal The validation stage fails the gate on any defect code, so a document with a malformed keyword does not ship Observation None, because a keyword is static text in a document, and nothing observes it while a run executes Evidence Watched to fire and to accept: a suite plants a retired head in a real template and validates every agent and template on disk clean Authoritative side The grammar data, which every keyword in a document conforms to Depends on Not answered Shape it refuses Not answered ### OBJECTOR Details Meaning What would disagree if the property stopped holding · a check, or none as declared debt Example objector: [check] one open fence per record | none Grounds [node:ver-falsification](https://banes-lab.com/records/reasoning/node-ver-falsification.md) How it is checked Checked by a structured-document validator that parses each document against the grammar and reports every defect by its shape Population Every agent and template document the validator walks, and every occurrence of the keyword in them Freshness A verdict stands until the grammar data or a document that uses the keyword changes Refusal The validation stage fails the gate on any defect code, so a document with a malformed keyword does not ship Observation None, because a keyword is static text in a document, and nothing observes it while a run executes Evidence Watched to fire and to accept: a suite plants a retired head in a real template and validates every agent and template on disk clean Authoritative side The grammar data, which every keyword in a document conforms to Depends on Not answered Shape it refuses Not answered ## Links to - [Invariant](https://banes-lab.com/records/reasoning/substrate-node-invariant.md) - [Reachable Check](https://banes-lab.com/records/reasoning/invariant-epi-reachable-check.md) - [Population](https://banes-lab.com/records/reasoning/node-ver-population.md) - [Constraint](https://banes-lab.com/records/reasoning/substrate-node-constraint.md) - [Refutation Condition](https://banes-lab.com/records/reasoning/node-ver-falsification.md)