This package is designed for typesetting the programmable elements in digital hardware, i.e., registers. Such registers typically have many fields and can be quite wide; they are thus a challenge to typeset in a consistent manner. Register is similar in some aspects to the bytefield and bitpattern packages. Anyone doing hardware documentation using LaTeX should examine those packages. Register requires version 2001/07/25 or newer of the float package. An example Perl module and script are provided, to convert the register specifications into structures suitable for, say, a pre-silicon test environment.