Well in the Star Trek map, every player has acces to develop for example this tech:
The tech does this (It upgrades the attack value by 1 on two types of ships):
<attachment name="techAbilityAttachment" attachTo="Light-Cruiser-Offensive-Weapons-Upgrade" javaClass="games.strategy.triplea.attachments.TechAbilityAttachment" type="technology">
<option name="attackBonus" value="1:Light-Cruiser"/>
<option name="attackBonus" value="1:Light-Cruiser-C"/>
There are no player specified, but I guess it only affects the player who develops the tech. The tech is still available for the other players to also develop. “techAbilityAttachment” techs do have limitations on what stats you can change. I know that you can change/upgade movement, attack, defense and add canBombard. I do this on the Star Trek map. Maybe there are some more things you can change, but you will have to look in the POS2.xml.
I just tested the Star Trek map, and it works like I describe here. Here is the XML: 0_1489183509813_star_trek_dilithium_war.xml