A file system exhibits structural dependence, which means that access to a file is dependent on its structure. For
example, adding a customer date-of-birth field to the CUSTOMER file shown in Figure 1.5 would require the four
steps described in the previous section. Given this change, none of the previous programs will work with the new
CUSTOMER file structure. Therefore, all of the file system programs must be modified to conform to the new file
structure. In short, because the file system application programs are affected by changes in the file structure, they
exhibit structural dependence. Conversely, structural independence exists when you can change the file structure
without affecting the application’s ability to access the data.