Don't make too many files

• Don't re-invent base map metadata
• Combine similar coverages or files
• Use the "parts" extension
• Make separate records when
  • sources
  • processing
  • projection
  are very different

    Data_Set_Structure:
        Data_Set_Part:
            Part_Name:
            Part_Type:
            Part_Description:
            Data_Set_Part:
                ...
        Data_Set_Part:
            ...