Tip A deep understanding of this article is important for ALL modders of ME2 and ME3. Please respect the modding community you are about to join enough to read it thoroughly.


DLC mods have been around for almost three years. During that time we've seen an enthusiastic, immediate adoption by content modders, but a much more gradual transition by mesh/textures modders. This is a good thing, as DLC mods are primarily meant for content mods. (We'll get to what's meant by that in a second.)

Toolset staff have recently seen a spike in questions from users on the forum and on Nexusmods about mesh/texture mods—typically armor/clothing mods—from creators who plan to release (or already have released) their creations as DLC mods. In almost all cases, these new mod creators are extremely inexperienced. They lack sufficient understanding of other options and don't realize that a DLC mod might not be the best way to distribute their mod. They know DLC mods are the new/easy/cool thing, and they don't properly evaluate the pros and cons of using them. As a result, more and more DLC mods are being released for game assets that don't really warrant this type of distribution.

With every new DLC mod created, more and more compatibility issues among mods will arise. Compatibility issues affect everyone from mod creator to other modders to users, and will ultimately make creating and using mods for ME2/3 harder over the long run. Ultimately, the decision of how to distribute is always up to each mod author, but informed decisions cannot be made without an adequate base of knowledge. Our goal is to provide that information and hope that folks use it to ease the burden on the community as much as possible.

First, let's start by briefly defining what DLC mods are and talking about why they are "meant" for content mods. This requires some historical context as to how content mods were installed prior to DLC mods.

What's a DLC Mod?

A DLC mod is any mod installed to the ME2 or ME3 DLC folder (we haven't tried making them for ME1, yet). They contain newly created or modded game assets inside a full folder structure identical to te base game. Each DLC mod is assigned a priority that controls how it's loaded in relation to other DLC. Think about it as "load order", a bit similar to Bethesda mods or using Texmod.

  • When priority is higher, any identical files override and are used in game
  • When priority is lower, any identical files are overridden and are not used in game

In addition, this relationship applies to any identical content IDs inside the TLK, CND, coalesced, and startup files.

The History of DLC Mods

The DLC mod method was discovered back in April 2014 by JohnP when working on JAM. Prior to this, very, very few content mods existed. ThaneMOD, MEHEM, and CEM were really the only three. While they generally modded different parts of the game, getting all of them to exist side-by-side was a difficult challenge. Why? Because all content mods need to modify some of the same, core game files: the TLK for text, the CND for plot conditionals, and the coalesced for a variety of game-related content. Note that at the time this didn't include the startup files for state event/codex/consequence maps (they wouldn't be moddable until later).

During 2012-early 2014, these three file types could only be modded by including exact game copies with changes edited in place. That meant that both MEHEM and ThaneMOD had to change the BIOGame_INT.tlk. It meant all three had to include the Conditionals.cnd. This was also back when DLC files were still kept inside SFARS. That meant that content needed to be inserted via MOD files, and installation order mattered. For example, MEHEM had to be installed first and ThaneMOD installed second, as ThaneMOD's changes needed to physically overwrite MEHEM's inside the SFAR.

Content modding prior to DLC mods, well...sucked. All content mods were inherently incompatible b/c they all needed to mod: BIOGame_INT.tlk, Conditionals.cnd, and Coalesced.bin, at minimum. And that's not considering any DLC equivalents of these files or any of the game's actual content files: PCCs. To top it off, none of these three file types could be handled by ModMaker, so nothing could be "patched in". ModMaker was useless for these files.

DLC mods were integral to the progression of content modding, because they resolved all of this. Now, multiple content mods could exist side-by-side, as each DLC had their own, specific TLK, CND, and coalesced files. DLC also used an overriding ability rather than an overwriting ability to control file loading, which was convenient. That meant authors could distribute patches when compatibility became an issue. Those patches could affect TLK, CND, coalesced, and PCC. Everything. As an added bonus, DLC mods were incredibly easy for users to install. Just copy and paste the folder into the ME3 DLC directory.

In short, DLC mods are what made content modding viable for ME3.

The Jump to Mesh and Texture Mods

When the DLC mod method was announced, the community didn't necessarily anticipate it being adopted by mesh and texture modders. Not because it couldn't also be of some value to that type of modding, but b/c the method was so necessary to the ability to create new content mods. MOD files were already the established method of releasing mesh edits and ModMaker had been created explicitly for that purpose. MOD files also had fewer compatibility issues since they worked by patching content into PCCs, rather than replacing or overriding them.

However, it did soon happen. In April 2015 the first DLC mesh/texture mod was released by AVPen on Nexusmods. From there, mesh and texture mods released as DLC have gradually snowballed.

The Problem with Excessive Numbers of DLC Mods

By now, hopefully you are starting to piece together in your mind why an excessive amount of DLC mods will become a problem and why this thread is necessary:

1. Compatibility Issues

More DLC mods mean not only more compatibility issues, but more complex compatibility issues. For example, it's not just about compatibility for mods A and B. What if mod B is patched by both mods A and C? And, what if one of those interferes with the functionality of the other? With each new DLC mod compatibility gets harder on the community. See the DLC Mod Compatibility Resource for details.

2. Mount priority duplication

Each mount priority needs to be unique. If two DLC mods share the same integer and are installed simultaneously, the game will not load them properly. More mods increases the chance that two will be assigned the same priority.

3. Mount priority "slots"

There are a limited number of integer "slots" between BioWare DLCs and the lowest-mounted DLC mod, and any two specific DLC mods. Once those integers are used up there is no way to mount a DLC mod in that location. That means if you need to mount below one mod but above another and there are no slots left, you are SOL. You can try to work around this with patches, but it will be a pain for you and your users.

When to Use a DLC Mod

Now that we've established that an excessive amount of DLC mods will have negative consequences, how do we solve the problem?

We solve it by the community not distributing every mod as a DLC mod. This means it's imperative that authors know when to distribute as a DLC mod and when not to. And the simple answer to that question is this:

When it is necessary.

DLC mods shouldn't be distributed because it's easiest for the user or it's more convenient for you as the creator. They should be distributed when it is necessary for the content you are creating. This leads to another question: what does "necessary" mean?

There are only two conditions in which a DLC mod is necessary:

  1. You need to edit/add content located in the TLK, CND, coalesced, or startup files.
  2. You need to load a new file into the game.

Anything beyond this does not REQUIRE a DLC mod. In that case, you should carefully consider your goals. From there, you can make a more informed decision about how to prepare and distribute your mod.

Alternatives to DLC Mods

Just because your mod doesn't meet the criteria above doesn't mean that all methods of distribution are appropriate. You have to carefully evaluate exactly how you intend to modify the files, as that will help determine how to distribute. Ultimately, your options are MOD, TPF, and loose PCCs. See Mod Formats and MOD101: Creating Mods for Mass Effect for more details.

1. TPFs

TPFs (or raw DDSes) should be used for all texture mods. MOD files have been long deprecated for textures and a mod that strictly alters textures should never be released in DLC mod form. If you want your texture mod to apply only to certain PCCs, both Texplorer and TPF Tools have PCC-level control.

2. MODs

ModMaker and MOD files are great for compatibility, but have restrictions on the type of content they can include: modified exports and new names are the only type of edits allowed. That means, no cloned exports, no edited names, and no new imports. And no binary edits. In other words, mesh modders, you can edit existing PCC content but you cannot add to it.

FYI, ModMaker isn't only for mesh mods; the Unreal properties of any existing export can be edited. MOD files are also capable of installing their contents into DLC mods, but only when explicitly made for that mod.

3. Loose PCCs.

If you add imports or exports to a file, modify existing names, or edit binary hex references, you cannot distribute via ModMaker. In this case, you must distribute as whole PCCs to be installed to the base game/BW DLC folder. This means that any DLC mod will override that file, if used. A patch would need to be created manually for compatibility.

BioX Files and Modding

We'll wrap this up by talking about the various PCC groups in ME2/3 and how they fit into the discussion of DLC mods. Certain files are "safer" to place in DLC mods than others—in relation to compatibility. The issue with creating excessive amounts of DLC mods still remains. See PCC File Format for more details.

1. BioH(ench)

These files control hench appearance, powers, and AI. There's a good chance that any two mods for these files are modding the same thing anyway, so releasing in DLC mod form is unlikely to create compatibility issues that need patching.

2. BioG(ear)

These files contain a variety of clothing, armor, and head meshes and materials. They are unlikely to be touched by content mods, but are frequently modded by mesh modders. Therefore, if released as DLC mods or as full PCCs, they are likely to have compatibility issues with other mesh mods. They are best released in this format when new outfits have been cloned in, or when all meshes have been overhauled, nullifying need for any other mods that alter the same file.

3. BioA(rt)

These files contain most environmental meshes and some meshes for decorator NPCs that are also found in BioG files. They can also contain streaming states and dialogues. Relatively few content mods touch them, but some do, especially when level editing. They are a riskier file for full replacement when it comes to mesh modding.

4. BioP(lot)

These files should never be included as DLC mods or loose files for mesh/texture mods. BioP files are core game plot files that control the loading of almost all other PCCs. Modding them should be avoided when at all possible, even for content modders. Mesh contents are rare, and any modifications should be handled with MOD files.

5. BioD(esign)

The bulk of ME2/3 PCCs consist of BioD files. These are heavily used by content mods, so mesh/texture mods should avoid distributing them as loose PCCs or DLC mods. It's of note that BioD files do contain meshes and texture references, especially for "named" supporting NPCs (along with combat AI, dialogue, streaming, and many other core game functions). Modifications to all these NPCs can be done via MOD files, but texture modifications will affect any other NPCs in the file that happen to reference the same texture.

Sample DLC Mods

It's always useful to provide some concrete examples of mods handled correctly, so here are a few:

1. EGM. — EGM is a large content mod distributed in DLC form. This makes sense, as it adds/modifies contents for the TLK, CND, coalesced, and startup. It also adds many new files to the game. Finally, it mods BioD and BioP files as needed, since it edits game plot and story content.

2. Urz on the Normandy. — UotN is a very small content mod distributed in DLC form. Despite its small size—and its edits to meshes and textures—it also alters conditionals, dialogue, and game text, and so must be distributed as a DLC mod. Finally, it mods BioD and BioP files as needed, since it edits game plot and story content.

3. EDI Default Outfit. — EDI Default Outfit is a mesh and texture mod that edits EDI's default outfit in her various BioH files. Ottemis distributes this in MOD/TPF form.

4. Alliance Armor Pack DLC. This mod by Kinkojiro adds new armors for Shepard—meshes and textures—in DLC mod form. All files in the mod are unique.


After reading this article, hopefully you have come to the conclusion that ease of use in the short term should not trump what's best for the community over the long term. Whether or not to create compatibility with any specific mod is always up to you as the author, but we hope that you now understand how to better integrate your work into the existing community. This will reduce compatibility issues overall, making less work for everyone.

Paragon250 This article was originally published by Giftfish on the ME3Explore Forum, and may still be discussed at that location.

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