Many strategies have emerged for integrating legacy applications into a current enterprise. Most of these strategies have focused on the development of ``wrappers'' (software that translates or maps between a common interface or interface description and the ``wrapped'' application). Occasionally the wrappers are written to make native calls to the applications. This is not always desirable or even feasible, however, as it involves modifying the legacy software and therefore requires a developer's knowledge that may have been lost. Because of this, the approach many wrappers take is to communicate with the legacy application via its input and output files. However, when input and output is complex - a typical situation for many applications, and engineering applications in particular - a substantial amount of knowledge and effort is required to make this wrapper function across the entire range of valid inputs and outputs. Often the scope of the interface is also reduced, resulting in lost functionality.
It is therefore desirable to have a way describe the structures of text files such that any valid file can be read and written without specialized software. Such a definition could be viewed as a computer-interpretable representation of knowledge about an application's interface. FSML was developed to satisfy this requirement. As a consequence, FSML can also be used for importing legacy application input and output files into a database or other data storage mechanism.