MuOnline Files Description

File Location
 File Name
 Description Why to edit?
 \Data\Local\ BuffEffect.bmd Effects that are done by some Item or during some event
 Translation(Name and Description columns)
 \Data\Local\    Credit.bmdNames of jobs and people that are created the game (In game if you click on credits you will see them)
 If you want your name also appear there :D
 \Data\Local\ Dialog.bmd All Texts that NPC says to player(Like when talking about quests)
 Translation(Message and Event Messages columns)
Also in 9 row  there is Home Page name.
\Data\Local\ Filter.bmd All Words that client will not display in Game(like bad words)
 If you want to add more words that players will not see if someone write them
 \Data\Local\ FilterName.bmd All not allowed character names to be created
 Add names that same as admins names - that players will not try to look like admin
 \Data\ Gate.bmd The gates that move player from one map to another map
 If you want to add new gates. After editing you should export it to server side gate.txt(usually in server data folder) that it will match.
\Data\Local\ Help.bmd Not relevant, not exists in new clients.
 
\Data\Local\ Item.bmd Names and configuration of items in the game.
 Translation or adding new items.
You also can edit item.txt in your server(usually in server data folder) and then import it to your clients item.bmd - that both server and client files will match.
If you decide to edit item.bmd and export to server side item.txt - then you should follow guide of special export using missing values editors - because in item.bmd is not enough information for creating server side item.txt
 \Data\Local\ ItemAddOption.bmd Stored configuration of Options for 380lvl Items, or   Halloween and Cherry Blossoms event option or   Partial charge option
 If you want to add more items options, I suggest to edit in server side ItemAddOption.txt file, and then to import to clients bmd file.
 \Data\Local\ ItemSetOption.bmd   Configuration of Ancient Sets that in the game(For each set what options available with what value)
 If you want to add more ancient sets or rename sets names.
You need that server side itemsetoption.txt will be same(after editing you can exports for server side file)
 \Data\Local\ ItemSetType.bmd Configuration of items that belong to ancient sets
 If you want to add\remove some items from ancient sets. The row number in that file matches to items row number in item.bmd. Set type number matches to ancitent set number in ItemSetOption file.
You need that server side itemsettype.txt will be same(after editing you can export for server side file)
 \Data\Local\ JewelOfHarmonyOption.bmd Configuration of option that are added with jewel of harmony
 Translation or configuation change(like price that needed to pay for level up)
You need that server side JewelOfHarmonyOption.txt will be same(after editing you can export for server side file)

 \Data\Local\ JewelOfHarmonySmelt.bmd Configuration of items that can have options of jewel of harmony.
Adding items to have jewel of harmony options . The row number in that file matches to items row number in item.bmd.
You need that server side JewelOfHarmonySmelt.txt will be same(after editing you can export for server side file)
 \Data\Local\ MasterSkillTree.bmd Configuration of skills tree
 
 \Data\Local\ Mix.bmd Configuration of Mixes
 Very complicated to edit.
 \Data\Local\ MonsterSkill.bmd Skills that monsters cast
 
 \Data\Local\ MoveReq.bmd Movements of player by the M menu
 Change names, add new movements.
You need that server side movereq.txt will be same(after editing you can export for server side file)
 \Data\Local\ NPCDialogue.bmd Texts that NPC says
 Translation
 \Data\Local\ NpcScript.bmd Not relevant, not exists in new clients. 
 \Data\Local\ Pet.bmd Configuration of pets
 
 \Data\Local\ Quest.bmd Configuration of quests
 Translate quest names. Quest configuration complicated to edit. but theoretical it is possible to add new quests like find item\kill monsters
 \Data\Local\ QuestProgress.bmd What texts will be on different stages of quest.
 
 \Data\Local\ QuestWords.bmd Texts from quests
 Translation
 \Data\Local\ ServerList.bmd List with server names
 Changing displayed server names
 \Data\Local\ ShopCategoryItems.bmd Configuation of items that are in the clients shop(In new clients there is shop for some cash points)
 
 \Data\Local\ ShopUI.bmd Configuation of interface of the shop
 Translation
 \Data\Local\ Skill.bmd Configuation of skills
 Translation or changing configuration of skills
 \Data\Local\ Slide.bmd Text that a running as slides in button of the screen(have some tips to new players)
 Translation or adding your own text
 \Data\Local\ SocketItem.bmd Socket Item configuration
 Translation of socket items names\texts
 \Data\Local\ Text.bmd Have the most of the texts that are in the game, including server names that displayed to player in main screen or servers home page addresses
 Translation or change of some texts

 message.wtf Have text that used by webzen mu.exe launcher
 If you use webzen mu.exe launcher that you can translate or change addresses of pages to yours.
 \Data\World##\ minimap.bmd Texts that shown on minimap
 Translation
 \Data\World##\ *.obj In that file are location and rotation of objects in the map
 Adding objects of your own to map
 \Data\World##\ *.map In that file are the look of the ground of each map(like grass,rocks,road, water)
 Changing the ground of the map
 \Data\World##\ *.att In that file are where player allowed to walk, where it is a safe zone, or where player will see just nothing(black ground)
 Changing where player allowed to go or where is safe zone.
 All Folders Except local folder
 *.bmd In that files are stored 3d models that game uses, for example in item folder will be items 3d models, in monsters folder will be monsters 3d models - you can preview that in 3d bmd -> smd preview and convert utility