The linker is used to configure block extenders. Its main functionality is to allow a user to right click on a block and then right click on a block extender, configuring either the disguise of the block extender, or in the wireless case, setting the destination of the block extender. It can be repeatedly used, it does not reset once it has disguised a block.
By right clicking in the air, you can reset the linker's linking and as such undisguise blocks.
It can also disguise sorting connectors, sorting interfaces, and sorting importers in the same way. The sorting connectors, interfaces and importers all completely appear to be the disguised block.