Many IT failures are caused by unclear or bad agreements and insufficiently organised expectation management between customers and suppliers. The target of ISPL is to diminish the number of IT failures by offering a well-defined process that can be used by both customer and the supplier to structure their acquisitions. An important role in the definition of a process and in the process to reach an agreement is played by words. Therefore, it is easy to appreciate the key role of a dictionary for the usability of ISPL. Furthermore, an important contribution to the usability of the ISPL framework is made by the consistency of the set of concepts defined in this dictionary.

By sharing consistent terminology and methodology, customers and suppliers achieve a better communication about the aims of IT projects and services and the means to achieve them.