diff --git a/core/src/commonMain/kotlin/cn/rdlevel/rdkt/core/RDLevel.kt b/core/src/commonMain/kotlin/cn/rdlevel/rdkt/core/RDLevel.kt
index 1658f05..d48bade 100644
--- a/core/src/commonMain/kotlin/cn/rdlevel/rdkt/core/RDLevel.kt
+++ b/core/src/commonMain/kotlin/cn/rdlevel/rdkt/core/RDLevel.kt
@@ -3,6 +3,9 @@ package cn.rdlevel.rdkt.core
 import cn.rdlevel.rdkt.core.settings.LevelSettings
 import kotlinx.serialization.Serializable
 
+/**
+ * A Rhythm Doctor custom level representation.
+ */
 @Serializable
 public data class RDLevel(
     public val settings: LevelSettings,