diff --git a/rpgJavaInterpreter-core/src/main/kotlin/com/smeup/rpgparser/execution/Configuration.kt b/rpgJavaInterpreter-core/src/main/kotlin/com/smeup/rpgparser/execution/Configuration.kt
index 6dd0a3933..50a1f088f 100644
--- a/rpgJavaInterpreter-core/src/main/kotlin/com/smeup/rpgparser/execution/Configuration.kt
+++ b/rpgJavaInterpreter-core/src/main/kotlin/com/smeup/rpgparser/execution/Configuration.kt
@@ -164,6 +164,10 @@ data class JarikoCallback(
     var onCallPgmError: (errorEvent: ErrorEvent) -> Unit = { },
     var logInfo: ((channel: String, message: String) -> Unit)? = null,
     var channelLoggingEnabled: ((channel: String) -> Boolean)? = null,
+    /**
+     * This is called for those statements mocked.
+     * @param mockStatement "Statement" where is get its name for the `println`.
+     */
     var onMockStatement: ((mockStatement: MockStatement) -> Unit) = { System.err.println("Executing mock: ${it.javaClass.simpleName}") }
 )
 
diff --git a/rpgJavaInterpreter-core/src/main/kotlin/com/smeup/rpgparser/parsing/ast/statements.kt b/rpgJavaInterpreter-core/src/main/kotlin/com/smeup/rpgparser/parsing/ast/statements.kt
index 8d3fed8d2..82d4041c3 100644
--- a/rpgJavaInterpreter-core/src/main/kotlin/com/smeup/rpgparser/parsing/ast/statements.kt
+++ b/rpgJavaInterpreter-core/src/main/kotlin/com/smeup/rpgparser/parsing/ast/statements.kt
@@ -85,6 +85,9 @@ abstract class Statement(
     abstract fun execute(interpreter: InterpreterCore)
 }
 
+/**
+ * For statements with this interface there isn't execution but will be called the callback `onMockStatement`.
+ */
 interface MockStatement
 
 interface CompositeStatement {