+ symbols next to planetary landing sites?

[Lannik]

Ive noticed them and sadly find myself ignorant as to their meaning. Is it some sort of security rating or affiliation?

[CasualGerman]

it is showing a security "rank"

[Eddie Gearknob]

Missions are available to attack or scan bases with security.

Rare firmwares are available from ++ and +++ sites by scanning 3 beacons in a time limit.

[Lannik]

Thanks! >250 hours into this game and I didnt know for sure since i try to avoid landing on planets due to how slow it can be at times.