Tuning 101

Core Concepts

Tuning XML

Sims 4 defines game data in XML, which is known as Tuning. Tuning XML can either define new game data or override existing game data. Here’s a practical example of tuning that defines a new trait.

<?xml version="1.0" encoding="utf-8"?>
<I c="Trait" i="trait" m="traits.traits" n="ZMilla:Trait" s="3678950568">
    <T n="display_name">0x2D954A47</T>
    <T n="icon">2f7d0004:00000000:8075ca84a3cefd11</T>
    <T n="trait_description">0x045E761F</T>
    <E n="trait_type">PERSONALITY</E>
</I>

We’ll go into much more detail later, but even at a glance it should be obvious that this XML defines a trait with a display_name, icon, trait_description, and trait_type.

Tuning Descriptions

To understand how to actually write valid tuning XML, EA releases a separate set of XML files that describe the tuning XML structure called Tuning Descriptions. These are normal XML files, but they use the .tdesc file extension.

These files are purely documentation and are not meant to be read directly. Instead, they are meant to be viewed by tools like Sims 4 Editor or Lot51’s Tuning Builder.

TDesc

Trait.desc viewed in S4E.

Combined Tuning

The Sims 4 contains over 100,000 XML tuning snippets. Individual files are slow to load, so they are compressed into much larger files called Combined Tuning. This means in order to browse the game’s XML tuning files, we first need to extract them back into individual files.

While several tools can do this, Sims 4 Editor includes a combined extractor and browser. Alternatively, you can use tdesc.lot51.cc to browse the files online without extracting.

Combined Tuning The tuning for the Ambitious trait viewed in S4E.

SimData

SimData is a custom binary format. SimData is not XML. However, it can be converted to and from XML using tools like Sims 4 Editor and Sims 4 Studio.

Some tuning fields require their data to be defined a second time in a SimData file. Which fields are required, if any, is defined in the .tdesc description files. This is shown on tdect.lot51.cc as an icon, and in S4E as an asterisk * (will likely switch to a similar icon later).