The Unity units library

This is the unity library, which is able to parse scientific unit specifications using a variety of syntaxes.

This is version 1.1-b1, 2022 April 10

The library is released under the terms of the 2-clause BSD licence.

The four syntaxes which the library (and VOUnits specification) refers to are:

• the FITS specifications, section 4.3 (see v3.0 (doi:10.1051/0004-6361/201015362; and v4.0 at the FITS specification page);
• OGIP memo OGIP/93-001 (postscript); and
• CDS's Standards for Astronomical Catalogues, Version 2.0.
• The VOUnits syntax. This is now the standard unit syntax for the Virtual Observatory, and intended to be as compatible as possible with the existing syntaxes (see section 2.12.1 of the specification for discussion of compatibility). The syntax is specified by the VOUnits specification.

The library includes a set of `known units', which draws heavily on the QUDT specification and models, in the sense that it incorporates a subset of the QUDT units, with a few astronomy-specific additions. Specifically it draws on QUDT v1.1, which was the current version at the time v1.0 of this library was released.

For discussion and build instructions, see the README.

Further links:

• The canonical home page is https://purl.org/nxg/dist/unity (please use this URI, rather than the one it redirects to, when citing the library)
• For source and jar downloads, see the downloads page.
• For the code, and to report problems, see the repository and bug-parade.

Documentation:

• C library (generated using doxygen; download).
• Javadocs (download).
• Various grammar files and test cases.

See the release notes.