The header & types

Every template begins with a --- frontmatter header declaring its inputs. The whole block is consumed (nothing leaks into the output); the body then uses bare ${ name } references — no inline types.

---
params {
  service:  iri
  endpoint: iri optional
  classes:  iri[] min 1
  tags:     string[] optional max 5
  people:   { id: iri, name: string optional }[] min 1
  limit:    int
}
---

• Sections are brace-delimited. params { … } is mandatory; example … { … } blocks are optional (see Examples & tooling). params and example are keywords only here, so any parameter name is allowed.
• Types: iri, pname, string, int, decimal, double, bool, date, dateTime, time, literal(<dt>), term, raw.
• Modifiers (in order): <type> ['[]'] ['optional'] ['min' N] ['max' N]. [] marks an array; min/max bound its length; optional marks that a value may be omitted.
• raw inserts verbatim with no escaping — the single auditable unsafe hatch, visible in the header.

The engine validates the whole context against the header up front (missing required, unknown key, wrong type, out-of-range cardinality). Typing is strict: "10" is not an int, a list is not a scalar.

Values

${ name } / ${ p.id } reference declared params or loop variables. The same reference serializes differently by construct: standalone → per its declared type; inside $"…" → string-escaped; inside $<…> → percent-encoded.

Keywords and type names are case-insensitive; variable names, IRIs, and string content are case-sensitive.