diff --git a/interface/definition b/interface/definition
new file mode 100644
index 000000000..33cb55aec
--- /dev/null
+++ b/interface/definition
@@ -0,0 +1,110 @@
+Type
+	SimpleType
+		Projection
+			prefix : SimpleType
+			id : String
+		ParameterRef
+			id: Int
+		Singleton
+			path: Path
+		EmptyType
+		Parameterized
+			baseType : SimpleType
+			typeArguments: SimpleType*
+	Annotated
+		baseType : SimpleType
+		annotations : Annotation*
+	Structure
+		parents : Type*
+		declarations: Definition*
+	Existential
+		baseType : Type
+		clause: TypeParameter*
+
+Source
+	packages : Package*
+	definitions: Definition*
+
+Package
+	name: String
+
+Definition
+	name: String
+	access: Access
+	modifiers: Modifiers
+	FieldLike
+		tpe : Type
+		Val
+		Var
+	ParameterizedDefinition
+		typeParameters: TypeParameter*
+		Def
+			valueParameters: ParameterList*
+			returnType: Type
+		ClassLike
+			definitionType: DefinitionType
+			selfType: Type
+			structure: Structure
+		TypeMember
+			TypeAlias
+				tpe: Type
+			TypeDeclaration
+				upperBound: Type
+				lowerBound: Type
+
+Access
+	Public
+	Qualified
+		qualifier: Qualifier
+		Protected
+		Private
+		Pkg
+
+Qualifier
+	Unqualified
+	ThisQualifier
+	IdQualifier
+		value: String
+
+Modifiers
+	isAbstract: Boolean
+	isDeferred: Boolean
+	isOverride: Boolean
+	isFinal: Boolean
+	isSealed: Boolean
+	isImplicit: Boolean
+	isLazy: Boolean
+
+ParameterList
+	parameters: MethodParameter*
+	isImplicit: Boolean
+MethodParameter
+	name: String
+	tpe: Type
+	hasDefault: Boolean
+	modifier: ParameterModifier
+
+TypeParameter
+	id: Int
+	typeParameters : TypeParameter*
+	variance: Variance
+	lowerBound: Type
+	upperBound: Type
+
+Annotation
+	base: SimpleType
+	arguments: String*
+
+enum Variance : Contravariant, Covariant, Invariant
+enum ParameterModifier : Repeated, Plain, ByName
+enum DefinitionType : Trait, ClassDef, Module, PackageModule
+
+Path
+	components: PathComponent*
+
+PathComponent
+	Super
+		qualifier: Path
+	This
+	Id
+		id: String
\ No newline at end of file
diff --git a/interface/src/main/java/xsbti/AnalysisCallback.java b/interface/src/main/java/xsbti/AnalysisCallback.java
index 70870965c..4c7bb8689 100644
--- a/interface/src/main/java/xsbti/AnalysisCallback.java
+++ b/interface/src/main/java/xsbti/AnalysisCallback.java
@@ -34,4 +34,6 @@ public interface AnalysisCallback
 	public void endSource(File sourcePath);
 	/** Called when a module with a public 'main' method with the right signature is found.*/
 	public void foundApplication(File source, String className);
+
+	public void api(File sourceFile, xsbti.api.Source source);
 }
\ No newline at end of file