EBNF Grammar

packet       = [rosetta_url "|"] identity "|" [timestamp "|"] operation "|" subject
               ["|" relation] ["|" evidence] ["|" temporal]

rosetta_url  = "@" domain "/" path
identity     = ("π:" | "ID:") agent_id [":" signature ":" gas]
timestamp    = "T:" digits
operation    = op_code "." confidence
op_code      = "OBS" | "INF" | "CON" | "MRG" | "SEK" | "YLD" | "PRD"
confidence   = digit digit                          (* 00-99 *)

subject      = tag value
tag          = "$" | "@" | "#" | "!" | "~" | "^"
value        = { alphanum | "_" | "." | "-" }

relation     = "RE:" agent_ref { "+" agent_ref }
             | evidence_ptr
evidence_ptr = ("←" | "<-") evidence_chain
evidence     = evidence_chain
evidence_chain = tagged_value { "+" tagged_value }
tagged_value = tag value

temporal     = "NOW" | "1H" | "4H" | "1D" | "1W" | "1M" | "HISTORICAL"
             | digits ("H" | "D" | "W" | "M")

direction    = "↑" | "↓" | "→" | "←"               (* legacy *)
             | "up" | "down" | "EQ" | "=>" | "<-"   (* ascii *)

agent_id     = { alphanum | "_" | "-" }
agent_ref    = agent_id
digits       = digit { digit }
digit        = "0" | "1" | ... | "9"
alphanum     = letter | digit

manifest     = "OBS.99" "|" manifest_subject "|" agent_ref "|" manifest_payload "|" temporal

manifest_subject = "@m.PROFILE"
                 | "@m.AUDIENCE"
                 | "@m.ONTOLOGY." name
                 | "@m.BUNDLE." name

manifest_payload = kv_pair { "+" kv_pair }
kv_pair      = "^" key ":" value
key          = { alphanum | "_" | "." }