The major cities (functions) are recorded but the small county roads and city roads are not. When troubleshooting, this high degree map is helpful in narrowing down and isolating where a problem or malfunction is.
A block diagram is a diagram of a system in which the main components or works are represented by cubes connected by lines which show the connections of the blocks. They are greatly utilised in engineering in hardware design, electronic design, software design, and process flow diagrams.
In electrical engineering, a layout may often begin as a quite significant level block diagram, getting increasingly more detailed block diagrams because the design develops, eventually ending in block diagrams comprehensive enough that every individual block is easily executed (at that point the block structure will be also a schematic diagram). This is known as top down style.  Geometric shapes are often used in the diagram to aid interpretation and clarify meaning of the process or version. The geometric shapes are connected by lines to signify association and direction/order of traversal. Each engineering discipline has their own significance for each shape. Block diagrams are used in every discipline of engineering. They're also a valuable source of theory building and educationally beneficial in non-engineering areas.
In process control, block diagrams are a visual language for describing actions in a complex system in which blocks are black boxes which represent mathematical or logical operations that exist in order from left to right and top to bottom, but not the physical things, like chips or radiators, that execute these operations. It is possible to make such block diagrams and execute their functionality with specialized programmable logic controller (PLC) programming languages.
In biology there is a growing use of technology fundamentals, techniques of analysis and ways of diagramming. There is a similarity between the block structure and what's named Systems Biology Graphical Notation. As it is there is use made in systems economics of this block diagram technique harnessed by control technology in which the latter itself is a program of control theory.
Block diagrams are typically used for higher level, less detailed descriptions that are meant to clarify overall concepts without issue for the details of execution. Compare this with the schematic diagrams and design diagrams used in electric engineering, which show the implementation details of electrical parts and physical structure.
For example, a block diagram of a wireless is not predicted to show each and every connection and dial and switch, but the schematic diagram is. The design of a wireless doesn't demonstrate the diameter of every connection from the circuit board, however, the design diagram will not.
Block diagrams rely on the principle of the black box in which the contents are concealed from view either to avoid being distracted by the details or because the details aren't known. We all know what goes in, we know what goes out, but we can not see how the box does its work.
An example of this is the function block structure, one of five programming languages found in part 3 of this IEC 61131 (see IEC 61131-3) standard that is highly formalized (see formal method ), with strict rules to the diagrams are to be assembled. Directed lines are used to link input variables to block inputs, and prevent presses to output factors and inputs from different cubes.