Symbols Drawing
Symbol level drawing is useful when creating large scale maps with intersecting and overlapping line features. For example, on a large-scale reference map with intersecting highways and streets, it helps you create high-quality representations of street and highway street intersections.
It is mostly useful in maps with cased lines as it creates overpass and underpass effects where the line features cross, which is a good way to show connectivity. Symbol level drawing can also be used to achieve other advanced effects. You can alter the draw order of features within feature layers. By using symbol level drawing, you can control the draw order of features on a symbol-by-symbol basis. This means features do not have to be drawn in the same order as feature layers that appear in ArcMap's table of contents (TOC). With symbol level drawing, you can control when a feature draws by controlling when the feature's symbol draws. Furthermore, when multilayer symbols are used, you can control the drawing order of individual symbol layers.
Graphic symbols are used on construction drawings to reference other drawings within the set. It is also used to list drawing notes, identify finishes and revisions. The same graphic is used for one purpose. Standard graphic symbols are used to present complete information concerning construction items and materials. These typical symbols are used so frequently in construction drawings that their meanings must be familiar not only to the preparer, but to the user as well. The main information sources for a particular symbol are the Military (Drawing) Standards (MIL-STD) and the American National Standards Institute (ANSI).