I dislike history sections, they are often verbose and wrong.
units was in v6.  NetBSD 1.0 implies it is/was in OpenBSD.

On Sat, Nov 30, 2024 at 11:48:32AM -0800, Evan Silberman wrote:
> diff /usr/src
> commit - 009b798eb105bd816df72071c0b273195535717e
> path + /usr/src
> blob - 57f405361568d301ed43d6326dbf3b6ad058a176
> file + usr.bin/units/units.1
> --- usr.bin/units/units.1
> +++ usr.bin/units/units.1
> @@ -212,6 +212,17 @@ the standard units library
>  .%R ISO/IEC 80000
>  .%T Quantities and units \(em Part 13: Information science and technology
>  .Re
> +.Sh HISTORY
> +A
> +.Nm
> +command first appeared in
> +.At v7 .
> +This version of
> +.Nm
> +appeared in
> +.Nx 1.0
> +and has been available since
> +.Ox 2.0 .
>  .Sh AUTHORS
>  .An Adrian Mariano Aq Mt adrian@cam.cornell.edu
>  or
> 
>