postscript point

[Martin Tarenskeen]

Hi,

I wanted to remove the indentation at the start of a score, and found

\paper {
  indent = 0\cm
}

in the manual. Wondering why to use \cm I soon discovered that it doesn't 
matter if I use 0\cm or 0\in or 0\pt or simply 0 without any unit. It all 
works. So now I use indent = 0


But my question is about something else. Reading NR 5.4.3 (Lilypond 2.18) 
I read: "points, 1/72.27 of an inch"

I have always learnt that a postscript point is defined as exactly 1/72 of 
an inch. Where does the (small) difference come from?

--

MT