| ### Modify existing interface programs

Examine the programs:

1. Understand the functions they perform
2. Understand jobs or on-line interfaces that invoke them
3. Determine their expected life
4. Modify these interfaces for year 2000 readiness if it saves effort, computing resources, or avoids building a bridge to undo what the existing interface does.
   - For example, if an existing interface converts VSAM to DB2, and a new bridge would convert DB2 back to VSAM, it may be preferable to remove the existing interface.
   - However, if the original interface will remain beyond the year 2000 conversion effort, it may be preferable to build a bridge to the interface; because the bridge can be removed without impacting the original interface as much as internal modifications would.
   - Existing interface programs can come from legacy systems or from a bridge in a previous partition; but if the interface comes from a legacy system rather than your year 2000 project, the interface modification activity is different from bridge construction in that it requires understanding existing code and the context in which it runs. Achieving this understanding may be more difficult than making the modifications themselves.

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