Hahahahahhah Hilarious.

  Define the default symbol for the imaginary unit, that is, the square root of negative one. The default Unicode codepoint for the imaginary unit. (DOUBLE-STRUCK ITALIC SMALL I)

  \u2148 := <<IMAGINARY_UNIT>>

  Also used for the imaginary unit (especially by electrical engineers, who use "i" to indicate current. (DOUBLE-STRUCK ITALIC SMALL J)

  \u2149 := <<IMAGINARY_UNIT>>

  Redefine the letter "i" to also be the imaginary unit

  i := \u2148

Hm, is there an archive of old versions of units.dat anywhere? Occasionally units get deleted from it - I used to keep old versions but I'd forgotten about this some time ago and haven't done so in a while. (Also that was several hard drive crashes ago so I no longer have the copies I made.)

On the kilogram: "I dislike having a prefixed unit as the base reference. What a horrible decision. Why don't you just have it go to ten and make ten a little louder?"

Exactly right.

nice, except there's more than 365 days in a year : )

  You have: 3 lightyears / 365.25 / 24 / 60 / 60 / 1000
  You want: miles
  	* 558.83525
  	/ 0.0017894361