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Backward compatibility

The API lets applications read the FCL independent of the FCL layout changes. For example, consider a scenario where an application directly accesses and interprets the on-disk FCL records. If the next VxFS release adds new records or changes the way the records are stored in the FCL file, the application needs to be rewritten or at least recompiled to accommodate for the changes (under previous VxFS versions).

With an intermediate API, the on-disk layout of FCL is hidden from the application, so even if the disk layout of FCL changes, the API internally translates the data returns the expected output record to the user. The user application can then continue without a recompilation or a rewrite.This insulates programs from FCL layout changes and provides greater compatibility for existing applications.