Model Definition

A model tells FZ how to read variables out of your input templates and how to pull results out of the output files. It is a plain dict (or a JSON alias in .fz/models/).

Common Fields

Field	Default	Purpose
varprefix	$	Marks a variable in input templates ($x, ${x}, ${x~default})
formulaprefix	@	Marks a formula (@{expr})
delim	{}	Delimiters around variable names / formula expressions
commentline	#	Comment marker introducing a formula-context line (#@ ...)
interpreter	python	Formula interpreter — python or R
output	—	Map of result column → extraction spec (see below)
timeout	—	Per-model run timeout in seconds; overrides FZ_RUN_TIMEOUT. None/0 disables it. (New in 1.2)

Output Extraction (updated in 1.2)

Each output entry says how to pull one result from a case's files. The spec can be:

• a shell command (implicit default, or explicit bash://) — "grep 'P:' out.txt | awk '{print $2}'"
• python://<expression> — native Python, no shell required
• jq://<filter> <file> — JSON via jq
• yq://<filter> <file> — YAML/JSON/XML/TOML via mikefarah/yq
• xpath://<expr> <file> — XML via xmllint --xpath
• a Python callable (Python API only) receiving the case directory as a pathlib.Path

Any of these may resolve to a list for vector-valued outputs (time series, profiles, spectra). Full details and helper reference: fzo — Output Command Forms.

See Also

• fzi / fzc — variable parsing and substitution
• fzo — Output Command Forms
• Formula Evaluation — @{...} expressions, interpreters, number formatting
• Model syntax reference in the FZ repo