"Data Enhancement"  is a process that involves adding new data elements to an existing database. An example of a common data append would be the addition of necessary data to a company's customer files. Companies often collect basic information on their clients such as phone numbers, emails, or addresses. A data append, or data enhancement, takes the information they have, matches it against a larger database of business data, allowing the desired missing data fields to be added.
The NAICS Association offers a wide range of Data Append Services including Phone Appends, NAICS & SIC Code Appends, and More.