The significant towns (functions) are listed but the small county roads and city roads are not. After troubleshooting, this elevated level map is useful in narrowing down and isolating in which a problem or error is.
In process management, block diagrams are a visual language for describing activities within a complex system where blocks are black boxes which represent mathematical or logical operations which exist in sequence from left to right and top to base, but not the physical entities, like processors or relays, that execute these operations. It is possible to make such cube diagrams and implement their functionality with specialized programmable logic control (PLC) programming languages.
For example, a block diagram of a radio isn't expected to show each and every link and dial up and change, however, the schematic diagram is. The design of a radio does not demonstrate the width of every connection in the circuit board, but the design diagram does.
In biology there's an increasing use of technology principles, techniques of analysis and ways of diagramming. There is some similarity between the block diagram and what's called Systems Biology Graphical Notation. Since it is there's use made in systems biology of this cube structure technique harnessed by control technology in which the latter itself is a program of control theory.
A block diagram is a diagram of a system where the principal components or functions are represented by cubes linked by lines which reveal the connections of the cubes.
An instance of this is that the function block diagram, one of five programming languages defined in part 3 of this IEC 61131 (view IEC 61131-3) standard that's quite formalized (see proper method ), with stringent rules for the diagrams must be assembled. Directed lines have been used to link input factors to block inputs, and block presses to output variables and inputs of other blocks.
Block diagrams are usually used for higher degree, less detailed descriptions that are intended to clarify general theories without difficulty for the particulars of implementation. Contrast this with the schematic diagrams and layout diagrams used in electric engineering, which reveal the implementation details of electric components and physical structure.
Block diagrams rely on the principle of the black box in which the contents are concealed from view to avoid being distracted by the details or because the details aren't known. We understand what goes in, we all know what happens, but we can't see how the box does its own work.
In electrical engineering, a layout may often start as a very higher level block diagram, becoming increasingly more detailed block diagrams because the design develops, eventually finishing in block diagrams detailed enough that each individual block is easily implemented (at which stage the block structure will be also a schematic diagram). This is known as top down layout.  Geometric shapes are often used from the diagram to help interpretation and clarify meaning of the procedure or model. Each engineering discipline has their own meaning for every shape. Block diagrams are employed in every discipline of engineering. They are also a valuable source of concept building and educationally beneficial in non-engineering disciplines.