Quote lines. Allowed lineType: title, element, comment. Two title levels are allowed: a title's content can hold elements, comments and sub-titles (themselves title lines), but a sub-title's content can only hold element or comment lines, never another title (titles are nested at most two levels deep). Allowed fields per line: label, quantity, unit, netUnitPrice, taxRateId, elementId, elementType, number, lineType (plus content on title and sub-title lines). element lines require quantity, unit, netUnitPrice and taxRateId. When an elementId (a catalog element or structure/ouvrage) is provided, only quantity is required: unit, netUnitPrice and taxRateId are inherited from the element when omitted (any value you pass takes precedence). If the elementId is a structure (ouvrage), its composition is loaded and saved into the quote. elementType must be an existing element type id, and takes precedence over the type of the referenced element. Line numbers are computed automatically (1, 1.1, 1.1.1…, comments are left unnumbered) unless the quote's autoLineNumber is false, in which case the number values you send are kept as-is (empty when omitted). element lines without elementId (free-text lines) default to elementType 3 (structure) unless sent, and always get searchType 3.