"A name\u2013value pair, key\u2013value pair, field\u2013value pair or attribute\u2013value pair is a fundamental data representation in computing systems and applications. Designers often desire an open-ended data structure that allows for future extension without modifying existing code or data. In such situations, all or part of the data model may be expressed as a collection of tuples ; each element is an attribute\u2013value pair."@en .