Voltage selector question

[Nick_the_'Nole]

I noticed on the back of my receiver I have an unusual assortment of choices for line voltage. It has settings for 110V, 117V and 130V in addition to the 220V and 240V. I know Hong Kong and some places use 100V, and 117V is the standard accepted US rating, but what's with the 110 and 130 settings?

I have the thing set on 117 running on a line voltage of ~119-120, and it's been working fine, I was just curious why all the extra options...

 

[Phil H]

Here is a link to voltages used around the world: http://www.kropla.com/electric2.htm