Traits & Preferences

1. What a trait actually does

At its simplest, a trait is a persistent or semi-persistent marker attached to a Sim. Other systems can check whether that marker is present and react accordingly. Traits are used for much more than CAS personality: preferences, lifestyles, fears, hidden gameplay flags, rewards, degrees, phone customization and many feature-specific states are all represented through Trait tuning.

Depending on the subsystem, the same Trait resource can serve several roles at once:

• classify a Sim inside a particular gameplay system;
• attach ongoing effects through one or more buffs;
• participate in statistics, commodities, modifiers or event-driven actions;
• act as a durable marker that tests can query later.

A trait therefore does not have to do something continuously. Sometimes the most important thing about it is simply that it exists on the Sim.

2. Trait types

The trait_type field classifies a trait for game systems and UI. The list below is generated from the current extracted game data.

3. Fields shared by Trait resources

Trait is the base tuning class. Personality traits, hidden markers, degree traits and many other trait families reuse its core fields, although each resource only includes the fields it actually needs.

Not every Trait resource should contain every base field. A hidden marker can be extremely small, while a personality or degree trait may be much richer. Compare against an EA trait from the same subsystem instead of filling fields merely because they exist on the base class.

4. Core buffs and other behavior

Many traits attach one or more buffs for as long as the trait is equipped. Modders commonly call these core buffs or trait buffs.

Trait present
  → attached/core buff active
  → modifiers, interactions and other ongoing effects become active

Traits can also change gameplay through buff replacements, interaction provisioning, statistics/commodities, event-driven loot, or simply by existing as markers that tests can check.

5. Preferences are a specialized trait family

Preference is a subclass of Trait. It inherits the base trait fields described above and adds fields used specifically by the preferences system. A preference tuning therefore uses c="Preference" i="trait", not the ordinary c="Trait" class.

Like / Dislike

trait_SimPreference_Likes_Decor_Cute
trait_SimPreference_Dislikes_Decor_Cute

Turn On / Turn Off

trait_Attraction_Characteristics_Funny_TurnOn
trait_Attraction_Characteristics_Funny_TurnOff

In both pairs, the subject stays the same and only the positive/negative state changes. Preference logic can therefore use familiar trait operations: add, remove, or test for the relevant trait.

6. Marker-only traits

A trait does not need a name, description, buff or visible UI. Marker-only traits store internal state that other tuning can test later.

State/event happens
  → hidden trait is present
Later test
  → checks that trait
  → different behavior becomes available

7. Trait IDs and SimData

Custom traits should use a 32-bit FNV hash (FNV32) for the tuning ID / Instance rather than FNV64. Their matching SimData must use the same Instance.

The XML root stores the tuning ID as a decimal number in s="...", while package/resource views generally show the Instance in hexadecimal. These are two representations of the same integer.

For the complete explanation of who creates the ID, how to generate it in Sims 4 Studio, and where decimal vs hexadecimal are used, see What Is Tuning? → IDs, comments and references.

Trait Tuning Instance  = 00000000:A1B2C3D4
Trait SimData Instance = 00000000:A1B2C3D4
                          └── same Instance

8. Real Trait XML example

The following shortened example uses EA’s trait_Unflirty resource. It keeps the real values needed to demonstrate the structure while omitting unrelated fields.

<I c="Trait" i="trait" m="traits.traits" n="trait_Unflirty" s="132589">
  <L n="actor_mixers">
    <U>
      <T n="key">13998<!--sim_Chat--></T>
      <L n="value">
        <T>132632<!--mixer_social_UnflirtyTrait_GiveColdShoulder_Targeted_Mean_AlwaysOn--></T>
        <T>132633<!--mixer_social_UnflirtyTrait_ReprimandPublicIntimacy_Targeted_Mean_AlwaysOn--></T>
      </L>
    </U>
  </L>
  <L n="ages">
    <E>TEEN</E>
    <E>ADULT</E>
    <E>ELDER</E>
    <E>YOUNGADULT</E>
  </L>
  <L n="buffs">
    <U>
      <T n="buff_type">132584<!--Buff_Trait_Unflirty--></T>
    </U>
  </L>
  <T n="cas_trait_asm_param">Unflirty</T>
  <L n="conflicting_traits">
    <T>27454<!--Trait_Romantic--></T>
    <T>361564<!--trait_RomanticallyReserved--></T>
    <T>362090<!--trait_LoveStruck--></T>
  </L>
  <T n="display_name">0x9A0E446B<!--Unflirty--></T>
  <T n="display_name_gender_neutral">0xD38C8E01<!--Unflirty--></T>
  <T n="icon" p="InEP03\UI\Icons\Traits\trait_Unflirty.png">2f7d0004:00000000:42e4e5e4fd94f29d</T>
  <E n="min_lod_value">MINIMUM</E>
  <L n="tags">
    <E>TraitPersonality</E>
    <E>TraitGroup_Emotional</E>
  </L>
  <T n="trait_description">0x2BE2E216<!--These Sims get Tense around Flirty Sims and seldom get Flirty themselves. It's difficult for them to be Romantic in public.--></T>
  <E n="trait_type">PERSONALITY</E>
  <V n="whim_set" t="enabled">
    <T n="enabled">132586<!--whimset_HasTraitUnflirty--></T>
  </V>
</I>

This one real trait demonstrates several important layers at once:

• s="132589" is the tuning ID in decimal form;
• ages limits eligibility;
• buffs attaches a core buff;
• conflicting_traits prevents incompatible personality traits;
• display_name, display_name_gender_neutral and trait_description point to STBL strings;
• icon references the UI image;
• actor_mixers gives the trait its own social mixer interactions;
• tags identifies the trait as a personality/emotional trait for related systems;
• whim_set connects the trait to a want/whim set;
• trait_type classifies it as PERSONALITY.

Quick reference