Yes you can withhold all the data but not a particular piece of data. For example if I salvage a few precursor wrecks with a single salvager, I may get engine tech, armour tech, ECM tech etc. If I am researching the engine tech in one system and all others in the home system I don't really want to download the engine tech to the home system with all the other data. Hope this makes it clearer.
Ian
Ah, I see. Haven´t played with 6.3/6.4 yet, so I wasn´t aware of the implications the new research anomalies brought with them.
Hm, thinking about it, how about the ability to _upload_ specific tech data into a ship again, I mean, it isn´t _gone_ it is just sitting in the computers of your research lab and if it fit into the salvager´s databanks and if that salvager was able to download that data to the labs, it sure should be possible to do the reverse.
Perhaps only salvagers (massive databanks that are part of the salvaging module) can hold/download/upload that huge amount of data, or how about creating a new module like "research databanks", so you could build a tech-courier?