# BNF grammar > PAG is defined by a context-free grammar written in Backus–Naur form (BNF), and its rules fall into five categories. Page: PAG · Grammar Canonical: https://banes-lab.com/pag/grammar#bnf-grammar PAG is defined by a context-free grammar written in Backus–Naur form (BNF), and its rules fall into five categories. The planning and coordination productions are the grammar's own records, each grounded to a reasoning record, and the statement, expression and flowchart rules expand the terminals those records leave open. The scan described in [well-formedness](https://banes-lab.com/pag/guide/well-formedness.md) reads tokens rather than patterns, although the grammar itself admits a pattern literal in a condition. ### Planning rules These rules cover [document structure](https://banes-lab.com/pag/guide/document-structure.md), the meta block, nodes, contracts, handoff gates, invariant records and the report. BNF grammar ```bnf # Instruction ::= ::= "---" "---" ::= | ε ::= | ε ::= "THIS" ::= "AGENT" | "WORKFLOW" | "PROTOCOL" | "POLICY" | "CHECKLIST" | "TEMPLATE" | "TASK" | "INSTRUCTION" | "PROMPT" | "COMMAND" | "TEST" | "DEBUG" | "VERIFICATION" | "DISTILLATION" | "AUDIT" | "TRANSLATION" | "COMPOSITION" ::= "IS" | "ENFORCES" | "EXECUTES" | "HAS" | "PERFORMS" | "PROVIDES" | "IMPLEMENTS" | "DEFINES" | "MANAGES" | "COORDINATES" | "GENERATES" | "RESOLVES" | "FINDS" | "FIXES" | "VERIFIES" | "CLASSIFIES" | "DISTILLS" | "ABSTRACTS" | "ELIMINATES" | "AUDITS" | "MEASURES" | "SCORES" | "CORRECTS" | "RENDERS" | "COMPOSES" | "FOLDS" ::= ::= + * ::= | ε ::= | ε # Meta block ::= "%%" "META" "%%" ":" + ::= "objective" ":" | "priority" ":" | "trust" ":" ("," )* | "jurisdiction" ":" "|" "external" ":" | "recursion_limit" ":" ::= (">" )* ::= "=" ("TRUSTED" | "UNTRUSTED" | ) ::= # Node ::= * ::= "#" "NODE" "—" "[" "·" "·" "·" "yields:" "]" ::= + ::= ::= "epistemic" | "conative" | "evaluative" ::= "ontology" | "teleology" | "analysis" | "reasoning" | "formalisation" | "verification" | "representation" | "termination" ::= "set-theory" | "logic" | "graph" | "algebra" | "analysis" | "optimisation" | "topology" | "computation" | "probability" | "information-theory" | "dynamical-systems" ::= "set" | "boolean" | "edge-list" | "ranking" | "procedure" | "artifact" | ::= "@purpose" ":" | "@axis_question" ":" | "@cue" ":" | "@genesis" ":" | "@mandatory" ::= "existence" | "difference" | "relation" | "structure" | "transformation" | "constraint" | "emergence" # Contract ::= "CONTRACT" ":" "input" ":" "transform" ":" + "output" ":" ::= "NODE" | | | ::= ("preserves" ":" ) | ε ::= ("," )* ::= ("constraints" ":" ) | ε ::= ("freshness" ":" "+" ) | ε ::= ::= ("handoff" ":" ) | ε ::= ("#" "OUTPUT" "CONTRACT" +) | ε ::= "{" ("." )* "}" ::= # Handoff gate ::= "HANDOFF" "GATE" ":" + ::= ("(" ")") | ε ::= ("rule_id" ":" "yields" ":" ) | ε ::= "(" "evidence" ":" ")" ::= "[check]" | "ASSERT" | "REQUIRE" ::= ::= | ε ::= "over" ":" "measured" ":" "/" ::= ::= | ::= ("refuse" ":" "before" ) | ε ::= | ::= ("standing" ":" "moved-set" ) | ε ::= "result" ":" "pass" "->" ("|" "->" "REPAIR" "(" "owner" ":" ")")+ "|" "unknown" "->" "BLOCKED" ::= "pass" | "fail" | "unknown" ::= "NODE" | "TERMINATE" ::= ::= "NODE" | ::= "#" "REPAIR" "EDGE" # Invariant block ::= "#" "CROSS-NODE" "INVARIANTS" + ::= "INVARIANT" ":" "over" ":" "binds" ":" "objector" ":" ( | "none") ::= ::= ::= ::= "[check]" # Report block ::= "REPORT" ":" + ::= "subject" ":" | "verdict" ":" | "domain" ":" "declared" "measured" | "populations" ":" | "inputs" ":" | "code" ":" | "output" ":" | "refusals" ":" | "unresolved" ":" | "completion" ":" "saturated" "complete" "verified" ::= "NODE" ::= ("," )* ::= ("," )* ::= "[" ("," )* "]" # Macro ::= "USE" "TEMPLATE" ::= # Rule ::= "RULE" ":" ::= ::= * + ::= "WHEN" ":" + ``` ### Statement rules These rules cover directives, actions, control flow and declarations. BNF grammar ```bnf # Directive ::= ::= | | | | | | | | | | | | | | | | | ::= | ε ::= "[" "]" ::= " " | "x" | ">" ::= | ε ::= ("@cue" ":" ) | ε # Action expression ::= * ::= | "EXECUTE" | "READ" | "WRITE" | "DELETE" | "REMOVE" | "ANALYZE" | "CREATE" | "FIND" | "REPORT" | "VALIDATE" | "VERIFY" | "COLLECT" | "EXTRACT" | "LINK" | "DETERMINE" | "CLASSIFY" | "INVESTIGATE" | "FILTER" | "COMPARE" | "CONVERT" | "MERGE" | "SPLIT" | "MARK" | "SORT" | "RANK" | "ORDER" | "INSERT" | "APPEND" | "ADD" | "MOVE" | "COPY" | "BACKUP" | "RESTORE" | "LOAD" | "ITERATE" | "ATTEMPT" | "ENFORCE" | "RENAME" | "FAIL" | "EXIT" | "RETURN" | "WAIT" | "SEND" | "REDUCE" | "PROPAGATE" | "FINALIZE" | "EVIDENCE" | "PREDICT" | "EXPLAIN" | "REFLECT" | "ABSTRACT" | "GENERALISE" | "DESCRIBE" | "FORMALISE" ::= "DISCOVER_RESOURCES" | "READ_RESOURCE" | "SEARCH_CONTENT" | "ANALYZE_CONTENT" | "EXTRACT_FACTS" | "CALCULATE_METRIC" | "COMPOSE_ARTIFACT" | "VALIDATE_ARTIFACT" | "PERSIST_ARTIFACT" | "EXECUTE_TOOL" | "REQUEST_DECISION" | "REPORT_RESULT" ::= "MUST" | "NEVER" | "ALWAYS" | "REQUIRED" | "MANDATORY" ::= | | ::= "SYSTEM" | "USER" | "SERVICE" ::= | | ε ::= "(" ")" ::= ::= ("," )* ::= | | # Control flow ::= | | | | | | ::= "IF" ":" + ("ELSE" "IF" ":" +)* ::= ("ELSE" ":" +) | ε ::= "FOR" "EACH" "IN" ":" + ::= "WHILE" ":" + ::= "TRY" ":" + "CATCH" ":" + ::= | ε ::= ::= "GOTO" ::= ":" ::= ::= "START" | "LOOP" | "END" | "STOP" ::= | ε ::= ("BACKTO" ) | ε # Declaration statement ::= "SET" "=" | "DECLARE" ":" ::= "string" | "number" | "boolean" | "array" | "object" | "file" | "context" # Transform statement ::= ::= "BACKUP" "TO" | "COPY" "TO" ::= "PERSIST_ARTIFACT" "TO" | "WRITE" | "EXECUTE_TOOL" "WITH" "timeout" ":" ::= ::= ::= "VALIDATE_ARTIFACT" "AGAINST" ::= | ε ::= ::= "CONTENT" | "FROM" | "INTO" | ::= ::= ::= # Discovery statement ::= ::= "DISCOVER_RESOURCES" "INTO" | "SEARCH_CONTENT" "FOR" "INTO" | "FIND" "IN" ::= "IF" "exists" ":" + | "ANALYZE" ::= | ε ::= "IN" | ε ::= ::= ::=