Editing Computer program (section)

===Coupling===
The levels of coupling from worst to best are:<ref name="se-ch8-226"/>

* ''Content Coupling'': A module has content coupling if it modifies a local variable of another function. COBOL used to do this with the ''alter'' verb.
* ''Common Coupling'': A module has common coupling if it modifies a global variable.
* ''Control Coupling'': A module has control coupling if another module can modify its [[control flow]]. For example, <code>perform_arithmetic( perform_addition, a, b )</code>. Instead, control should be on the makeup of the returned object.
* ''Stamp Coupling'': A module has stamp coupling if an element of a data structure passed as a parameter is modified. Object-oriented classes work at this level.
* '' Data Coupling'': A module has data coupling if all of its input parameters are needed and none of them are modified. Moreover, the result of the function is returned as a single object.