> I wasn't aware of the fact that the continental
> slope was part of it as well, and that there are parts beyond that,
> that can be claimed

Yes, "continental margin" seems to be the phrase of choice, to avoid
confusion. Cribbing from Prescott again, there are two definitions of
the edge of the continental margin that come (I think; he's a bit
unclear, here) from Article 76 of the UN Conference on the Laws of
the Sea. They apply in those situations when the continental margin
extends beyond the 200nm limit.

1) A boundary may be drawn not more than 60nm seawards of the foot of
the continental slope. (Simple!)
2) A boundary may be drawn between those points seaward of the foot
of the continental slope where the thickness of sedimentary rocks is
at least 1% of the shortest distance between such points and the foot
of the continental slope. (This is known, apparently without irony,
as "the Irish formula".)
So if you have thick offshore sedimentary rocks (or even if you
*claim* to have thick offshore sedimentary rocks!) you can push your
margin more than 60nm beyond the edge of the slope. Prescott says
there are only a few places this occurs; outside of Antarctica they
are: off Montevideo and Oranjemund, and at the heads of the Arabian
Sea and the Bay of Bengal.

States can choose whichever options suit them best, but there are
absolute upper limits to the possible claims:
1) They should not extend more than 350nm beyond the state's coastal
baselines.
2) They should not extend more than 100nm beyond the 2500m isobath.

Grant