  Accurate and comprehensive diatomic molecular spectroscopic data have long
been vital in a wide variety of applications for measuring and monitoring
astrophysical, industrial and other gaseous environments. These data are also
used extensively for benchmarking quantum chemistry and applications from
quantum computers, ultracold chemistry and the search for physics beyond the
standard model. Useful data can be highly detailed like line lists or summative
like molecular constants, and obtained from theory, experiment or a
combination. There are plentiful (though not yet sufficient) data available,
but these data are often scattered. For example, molecular constants have not
been compiled since 1979 despite the existing compilation still being cited
more than 200 times annually. Further, the data are interconnected but updates
in one type of data are not yet routinely applied to update interconnected
data: in particular, new experimental and ab-initio data are not routinely
unified with other data on the molecule. This paper provide information and
strategies to strengthen the connection between data producers (e.g. ab-initio
electronic structure theorists and experimental spectroscopists), data
modellers (e.g. line list creators and others who connect data on one aspect of
the molecule to the full energetic and spectroscopic description) and data
users (astronomers, chemical physicists etc). All major data types are
described including their source, use, compilation and interconnectivity.
Explicit advice is provided for theoretical and experimental data producers,
data modellers and data users to facilitate optimal use of new data with
appropriate attribution.

Chemical Physics;Solar and Stellar Astrophysics