fan-in and fan-out

The concept of fan-in and fan-out refers to the hierarchical calling situation between application modules.
Fan- in: refers to the number of upper-level modules that directly call the module. A large fan-in indicates that the multiplexing program of the module is high.
Fan-out: refers to the number of subordinate modules directly called by the module. A large fan-out indicates a high module complexity, requiring control and coordination of too many subordinate modules; but a small fan-out (eg always 1) is not good either.
Excessive fan-out is generally due to the lack of intermediate levels, and modules at intermediate levels should be appropriately increased. If the fan-out is too small, the lower-level module can be further decomposed into several sub-function modules, or merged into its upper-level module.
A well-designed software structure usually has a large fan-out at the top level, a small fan-out in the middle, and a large fan-in in the bottom-level module. A


more appropriate way of saying is: a description method for describing load conditions