Most of the callable functions in NAV are designed to handle a very specific set of data or conditions and have no general-purpose use, for example, the routines to update Check Ledger entries during a posting process are likely to apply only to that specific function. If we are making modifications to a particular application area within NAV, we may find functions that we can utilize, either as is or as models for our new functions.

There are also many functions within NAV that are relatively general purpose. They either act on data that is common in many different situations, such as dates and addresses, or they perform processing tasks that are common to many situations, such as providing access to an external file. We will review a few such functions in detail, then list a number of others worth studying. If nothing else, these functions are useful as guides for showing how such functions are used in NAV. The various parameters in these explanations are named to assist with your learning, not named the same as in the NAV code (though all structures, data types, and other technical specifications match the NAV code).

If we are using one of these functions, we must take care to clearly understand how it operates. In each case, we should study the function and test with it before assuming we adequately understand how it works. There is little or no documentation for most of these functions, so understanding their proper use is totally up to us. If we need a customization, that must be done by making a copy of the target function and then modifying the copy.