A constant is a dict with the keys id, category, material_or_item, quantity, value_text, unit, unit_si, condition, source, date_opened (a term date(Y,M,D)), used_by_tool_url, engine_file, engine_symbol (lists of strings), notes, withheld (true or false) and withheld_hosts (list of strings), plus value and value_si (floats). Text values are strings. source is a dict with the keys publisher, title, url and type.

When withheld is true the publisher does not allow republication: the dict has no value and no value_si key, value_text is the empty string, and the value is read at the URL of the source. value_si is also absent when the table leaves it empty.

 all(-Constants:list(dict)) is det

Every constant, in table order.

 by_id(+Id, -Constant:dict) is semidet

The constant with the given id (atom or string), for example 'CON-001'. Fails when the id is unknown.

 search(+Query, -Constants:list(dict)) is det

The constants whose id, category, material, quantity, condition, publisher or notes contain every word of Query, ignoring case. An empty query returns the empty list.

 sources(-Sources:list(dict)) is det

Each distinct source of the table once, sorted by publisher, then title, then URL (code order, as the byte order of the Go module for this table).