conventional quantity value 

Synonyms: conventional value, conventional value of a quantity
https://doi.org/10.1351/goldbook.08016
Quantity value attributed by agreement to a quantity for a given purpose.
Notes:
  1. Sometimes a conventional quantity value is an estimate of a true quantity value.
  2. A conventional quantity value is generally accepted as being associated with a suitably small measurement uncertainty, which might be zero.
  3. In quality assurance and quality control in chemistry, a conventional quantity value, which may be a consensus property value, is often termed "assigned value".
Examples:
  1. Conventional quantity value of a given mass standard, \(m = \pu{100.00347 g}\).
  2. Relative atomic mass for carbon as listed in the IUPAC Green Book.
  3. Consensus property value of the measured values of an interlaboratory comparison.
Source:
PAC, 2021, 93, 997. 'Metrological and quality concepts in analytical chemistry (IUPAC Recommendations 2021)' on page 1004 (https://doi.org/10.1515/pac-2019-0819)