How do you explain this:

I'm not asking this for fun, I have a real problem here.

I need to use lightISH background, but the objects aren't visible enough with nice background tone.

I'm studieng this and my teacher uses windows version, so he can't help in every way.

He's index color #9 is 242,242,242.

If I have understood right, it would be wise to use indexed color as background, because then ACAD notices when there are layers with same indexed color and changes them, so they will show up more clearly.

If I choose some random true color that is close to that indexed layer color the objects does not show clearly, sine ACAD does not chenge their color values then.

If your number #8 = 178,178,178 was a typo, then we could still have theoretically "global" indexed colors.

But why on earth, we do not have indexed color that is gray and between 192-244 ?!?!