Software products are generally delivered and installed in a standard manner. However, there is no such thing as a "standard" organisation or environment. Most products provide a number of opportunities to customise or tailor the product to meet the specific requirements of the organisation, environment or even a particular application.
Some typical examples of customisation are
These must generally be written in assembler, either because other programming languages are simply not supported or for performance reasons. Additionally, extensive knowledge of the product involved is also required.
I have extensive experience of customising system products for customer environments and to meet customer requirements. This service can include