conventional true value

https://doi.org/10.1351/goldbook.C01316
Value attributed to a particular quantity and accepted, sometimes by convention, as having an uncertainty appropriate for a given purpose. Examples are the CODATA recommended values of fundamental physical constants.
Sources:
PAC, 1996, 68, 149. (A glossary of terms used in chemical kinetics, including reaction dynamics (IUPAC Recommendations 1996)) on page 162 [Terms] [Paper]
VIM [Terms] [Book]