Not all data formats are suitable for long term storage and future usage.  Format and software versions change, become obsolete, or require proprietary software to be use.

 Here is a list of Common File Formats and the preferred file formats for preservation and access.

These formats are based on platforms that are low-cost or free and have a stability.  A repository will be able to support these format and guarantee long term preservation. In some cases, your data might require emulation or a proprietary software to view and examine . In these cases, A data repository has different levels of support governed by a preservation and access policy.  For example, the University of Minnesota Digital Conservancy offers the following levels of support: Full Support (Level 1)

• Will take all reasonable actions to maintain usability.
• Actions may include migration, emulation, or normalization.
• Will ensure access and data fixity.

Limited Support (Level 2)

• Will take limited steps to maintain usability.
• May actively transform a file from one format to another to mitigate format obsolescence.
• Will ensure access and data fixity.

Minimal Support (Level 3) 

• Will provide for access to the item in its submission file format only.
• Will work to ensure data fixitty