That is not quite correct.

If we define (for

__this__ example only) a ceiling of 30% for the

__first stop__, we can draw a line thirty percent of the distance between the ambient pressure line and the M-value line. It will not parallel the ambient line, but rather extend out at the same relative distance from the two reference lines. In fact, most of the early GF depictions did exactly that: there was an AP line, an M-value line, and between them, GFLo and GFHi lines, all spreading out visually like rays of sunlight.

View attachment 482572
Shearwater, in order to declutter their graphic, eliminated the GF lines, since

**for any given max depth**, there is only one point starting at a given max depth and rate of ascent where GFLo is reached, and one point (the surface) where GFHi is reached.

We are struggling here because we forget that any new GFLo point will come about because (as

@doctormike pointed out) it must have required a new max depth. As he stated, the ceiling occurs when we reach 30% of M-value for the leading compartment. Having a dotted line that extends past that point to the right is no longer at 30%, because that line is sloped at 30/80 for that max depth only.

Apples and oranges, I'm afraid.