(You can find mention of this in several places, including the SWTOR official forums, so I am not the originator of this, I am simply reposting it here because I couldnt find mention of it)
The trick is simple enough. It allows you to RE any item modification crafted by another player to give you a chance to learn the schematic to be able to craft it yourself.
Great way of learning those pesky ops/HM schematic drops such as the 27 modification schematics so you can craft and sell them yourself for a nice profit.
Note: Of course you need the necessary Crafting skill to be able to RE the modification (such as armstech for barrel, cybertech for armoring etc)
The trick explained:
- Get a player crafted mod from GTN/Another player.
- Place it into an item slot on a piece of armor or similar.
- Go to a mod station and rip it out into your inventory again. This is the "glitch" part that removes he crafted flag from the mod.
- RE the mod and it gives you the chance to learn a schematic from it.
- Craft the item yourself and profit!
Hope you found this useful!