[PvK]

They are three different kinds of shielding, with no overlapping effects at all. This is actually the same as in the unmodded game, except that in Proportions, the non-gravitational shields are not only unique ruins tech.

That is, regular and phased planetary shield generators that give shield points help against (almost all) weapons in combat.

The planetary grav shield stops planet-destroying tectonic bombs, which are launched from strategic range (not in tactical combat). That's all it does, and it's the only thing that stops that besides intercepting the ship. It's the only way to directly protect against a surprise backstab attack with a tectonic bomb. It doesn't protect against tactical combat attacks (including the continental tactical tectonic bombs in Proportions, which are delivered in tactical combat).

The system grav shield prevents several other stellar manipulations within the system: black holes, nebulae, star destruction, and warp point open/close. No tactical shield points, and no protection from tectonic bombs.

"Negates all damage of 10 or less" is Malfador's old wording for the old emissive effect before the latest two patches. It used to only have any effect on hits weaker than the threshold value.

"Deflects 10 points of damage per hit" is a more accurate description of what all emissive effects actually do in the current Version of the game. 10 is subtracted from each hit against the ship, unless it is a damage type that bypasses armor.

PvK