“A layout drawing depicts design development requirements. It is similar to a detail, assembly, or installation drawing, except that it presents pictorial, notational, or dimensional data to the extent necessary to convey the design solution used in preparing other engineering drawings. Except as noted…a layout drawing does not establish item identification.”1
In my experience, a layout will often combine the attributes of many other drawing types. It is never used for rate production, so the rules are looser.
In the DoD hardware legacy, a layout was considered a “Level 1 drawing”, used for conceptual and Developmental design.
Footnotes- ASME Y14.24, section 2.1.[↩]