NEWS.md
In constants: Reference on Constants, Units and Uncertainty

constants 1.0.1

Fix compatibility with units 0.7-0.

constants 1.0.0

Update to version 8.1, the 2018 CODATA recommended values (#7 addressing #6). This version contains some breaking changes that are necessary to streamline future updates and provide a stable symbol table:

The codata table includes the absolute uncertainty instead of the relative one. Thus, the rel_uncertainty column has been dropped in favour of the new uncertainty. Also, columns have been slightly reordered.
Symbol names for constants have changed. The old ones were hand-crafted and thus unmanageable. This release adopts the ASCII symbols defined by NIST in their webpage, except for those that collide with some base R function. In particular, there are two cases: c, the speed of light, has been renamed as c0; sigma, the Stefan-Boltzmann constant, has been renamed as sigma0.
Constant types, or categories, (column codata$type) adopts the names defined by NIST in the webpage too. Some constants belong to more than one category (separated by comma); some others belong to no category (missing type).

There are some new features too:

In addition to the codata data frame, this release includes codata.cor, a correlation matrix for all the constants.
In addition to syms_with_errors and syms_with_units, there is a new list of symbols called syms_with_quantities (available if the optional quantities package is installed), which provides constant values with uncertainty and units.
Experimental support for correlated values in syms_with_errors and syms_with_quantities is provided (disabled by default; see details in help(syms) for activation instructions).