Be updated often enough to be useful, if currency is important. Have back files available if needed, in a format consistent with current file retrievability and maneuverability. Have the ability to be archived, if necessary. Demonstrate that production quality is satisfactory for the proposed use. Vendor-produced documentation is thorough and clear.
Customer support is available from the vendor during the library's working hours.
Price penalties, if any, for different formats have been investigated. It is clear whether purchasing or leasing the resource is more economical. When the title is available from multiple vendors, selecting a format already present and familiar to library users. Resources should be in the most commonly used and appropriate language for the subject matter, especially in textual resources. Published reviews of the resource should be consulted.