<P> Each view or section is a separate set of projections, occupying a contiguous portion of the field of the drawing . Usually views and sections are called out with cross-references to specific zones of the field . </P> <P> Often a drawing is divided into zones by a grid, with zone labels along the margins, such as A, B, C, D up the sides and 1, 2, 3, 4, 5, 6 along the top and bottom . Names of zones are thus, for example, A5, D2, or B1 . This feature greatly eases discussion of, and reference to, particular areas of the drawing . </P> <P> As in many technical fields, a wide array of abbreviations and symbols have been developed in engineering drawing during the 20th and 21st centuries . For example, cold rolled steel is often abbreviated as CRS, and diameter is often abbreviated as DIA, D, or ⌀ . </P> <P> With the advent of computer generated drawings for manufacturing and machining, many symbols have fallen out of common use . This poses a problem when attempting to interpret an older hand - drawn document that contains obscure elements that cannot be readily referenced in standard teaching text or control documents such as AMSE and ANSI standards . For example, AMSE Y14. 5M 1994 excludes a few elements that convey critical information as contained in older US Navy drawings and aircraft manufacturing drawings of World War 2 vintage . Researching the intent and meaning of some symbols can prove difficult . </P>

What should one include on the view of the assembly model to reference the bill of materials