Covert Data Link

Covert Data Link allows you to use old friendly codes for ships and planets for all purposes that you would normally use a friendly code for. This means even if a player changes their friendly code, you can still use it the next turn with a 100% success rate. You can do all the normal things you could do with a matching friendly code, such as travel through minefields, beam up minerals from a planet, use Harmonic Weapon Modulation against a ship, etc., even though the planet or ship has changed its friendly code.

Odds of Success

For every turn after the 1st turn of using an old friendly code, the odds of success of the FC working are reduced by 10%. So 2 turns after a friendly code has changed, there is a 90% success rate. 3 turns afterwards there is an 80% chance, etc. This chance of success is calculated for every individual ship using that FC. If one of your ships fails in using a friendly code, that code is permanently revoked, and no other ships can use it.

Notes

Explanation of Covert Data Link by Joshua at PlanetsCon 2022