How much time to you have on your hands?

That works too... haha. I skimmed that section too quickly, but my quote also covers it, if in a more roundabout way. Nice to have the direct rule in question though.

It's really simpler than all this. Ignore whether the character is colossal or giant at first. Ask yourself if they could draw line of fire as they are. Then consider if they could draw it if they were at a higher elevation to account for being a colossal or giant.

An elevated terrain border blocks line of fire if the higher point on the line isn't in a square with that line.

Blocking terrain blocks line of fire if it's on the same level as the lower point on the line of fire.

Elevated terrain borders and blocking terrain don't block if they are beneath the lowest point on the line of fire. This is the only rule where being a giant or colossal really comes into play.

Noted, and made corrections to the original

Agreed, but for some peoplethe visualization makes the difference. Feel free to use this where needed.

Ok if outdoor blocking terrain is as high as the highest elevation, if there is only one elevation can giants see over it or does it basically go on forever?

I'm not clear what you are asking. Does this diagram represent the situation in your question?

. . . . . . . .
. . . . . . . .
. X .|. b .|. T
. . .|. . .|. .
. . . . . . . .

Where X is a colossal?

There's a line of elevated border, two of them in fact, between X and T, so if either is a , they cannot draw an unblocked line of fire, even without the blocking terrain. If BOTH X and T are or , then they can draw line of fire at an elevation higher than any of the map features and can draw line of fire to each other. (Unless this was indoors, then the blocking terrain would "go all the way up", or, in technical terms, exist at all levels of elevation, and block pretty much everything.)

Edit: Hmm, I really need to figure out a good way to indicate whether elevated terrain lines indicate hills or pits. In any event, the above map is meant as having a hill.

On indoor maps, a square of blocking terrain exists at every elevation.

On outdoor maps, a square of blocking terrain only exists at whatever level it is on.
If an outdoor map only has one elevation (level one across the whole map) giants can see eachother over any blocking terrain, because the giants can draw lines of fire at level 2, even if there is no printed level 2 terrain on the map.

From Great Size on the PAC: