In addition, the mod name will be greyed out and italicized.
If you want to use the mod despite this fact, you can right-click the mod and select Ignore missing data to remove the flag.
Not counting the game's initial release or its pre-beta stages, the game has received 48 updates.
Click on an update number in the table to the right to go to that section. This update is the official client and server release for native Mac and Linux Support.
If a lightning icon with a red minus sign appears, the mod will will not overwrite files from any other mod but will have one or more of its files overwritten by a higher priority mod.