diff --git a/opast.cc b/opast.cc
index a5704c4..da080db 100644
--- a/opast.cc
+++ b/opast.cc
@@ -304,6 +304,7 @@ struct T_ParserImpl_
 	enum class E_InstrType {
 		CALL ,
 		IF ,
+		INPUT ,
 		PIPELINE ,
 		PROFILE ,
 		PROGRAM ,
@@ -319,6 +320,7 @@ struct T_ParserImpl_
 
 		add( "call" , E_InstrType::CALL );
 		add( "if" , E_InstrType::IF );
+		add( "input" , E_InstrType::INPUT );
 		add( "pipeline" , E_InstrType::PIPELINE );
 		add( "profiling" , E_InstrType::PROFILE );
 		add( "program" , E_InstrType::PROGRAM );
@@ -414,27 +416,21 @@ struct T_ParserImpl_
 
 	// ---------------------------------------------------------------------
 
-	void parseCallInstruction(
-			T_InstrListNode& instructions ,
-			T_SRDList const& input ) noexcept;
-	void parseIfInstruction(
-			T_InstrListNode& instructions ,
-			T_SRDList const& input ) noexcept;
-	void parsePipelineInstruction(
-			T_InstrListNode& instructions ,
-			T_SRDList const& input ) noexcept;
-	void parseProfileInstruction(
-			T_InstrListNode& instructions ,
-			T_SRDList const& input ) noexcept;
-	void parseProgramInstruction(
-			T_InstrListNode& instructions ,
-			T_SRDList const& input ) noexcept;
-	void parseSetInstruction(
-			T_InstrListNode& instructions ,
-			T_SRDList const& input ) noexcept;
-	void parseTextureInstruction(
-			T_InstrListNode& instructions ,
-			T_SRDList const& input ) noexcept;
+#define M_DPARSER_( NAME ) \
+	void parse##NAME##Instruction( \
+			T_InstrListNode& instructions , \
+			T_SRDList const& input ) noexcept
+
+	M_DPARSER_( Call );
+	M_DPARSER_( If );
+	M_DPARSER_( Input );
+	M_DPARSER_( Pipeline );
+	M_DPARSER_( Profile );
+	M_DPARSER_( Program );
+	M_DPARSER_( Set );
+	M_DPARSER_( Texture );
+
+#undef M_DPARSER_
 
 	// ---------------------------------------------------------------------
 
@@ -576,6 +572,7 @@ void T_ParserImpl_::parseInstructions(
 		switch ( *instrMap.get( iword ) ) {
 			M_CASE_( CALL , Call );
 			M_CASE_( IF , If );
+			M_CASE_( INPUT , Input );
 			M_CASE_( PIPELINE , Pipeline );
 			M_CASE_( PROFILE , Profile );
 			M_CASE_( PROGRAM , Program );
@@ -603,9 +600,12 @@ P_InstrListNode T_ParserImpl_::parseBlock(
 
 /*----------------------------------------------------------------------------*/
 
-void T_ParserImpl_::parseCallInstruction(
-		T_InstrListNode& instructions ,
-		T_SRDList const& input ) noexcept
+#define M_INSTR_( NAME ) \
+	void T_ParserImpl_::parse##NAME##Instruction( \
+			T_InstrListNode& instructions , \
+			T_SRDList const& input ) noexcept
+
+M_INSTR_( Call )
 {
 	if ( input.size( ) == 1 || input[ 1 ].type( ) != E_SRDTokenType::WORD ) {
 		errors.addNew( "function identifier expected" ,
@@ -621,9 +621,7 @@ void T_ParserImpl_::parseCallInstruction(
 
 /*----------------------------------------------------------------------------*/
 
-void T_ParserImpl_::parseIfInstruction(
-		T_InstrListNode& instructions ,
-		T_SRDList const& input ) noexcept
+M_INSTR_( If )
 {
 	if ( input.size( ) == 1 ) {
 		errors.addNew( "expression and 'then' block expected" ,
@@ -652,9 +650,34 @@ void T_ParserImpl_::parseIfInstruction(
 
 /*----------------------------------------------------------------------------*/
 
-void T_ParserImpl_::parsePipelineInstruction(
-		T_InstrListNode& instructions ,
-		T_SRDList const& input ) noexcept
+M_INSTR_( Input )
+{
+	if ( input.size( ) < 2 || !input[ 1 ].isText( ) ) {
+		errors.addNew( "input identifier expected" ,
+				input[ input.size( ) < 2 ? 0 : 1 ].location( ) );
+		return;
+	}
+	if ( input.size( ) > 3 ) {
+		errors.addNew( "too many arguments" , input[ 3 ].location( ) );
+	}
+	if ( input.size( ) >= 3 && !input[ 2 ].isNumeric( ) ) {
+		errors.addNew( "default value expected" , input[ 2 ].location( ) );
+	}
+
+	const bool hasDefault( input.size( ) >= 3 && input[ 2 ].isNumeric( ) );
+	auto& instr( ([&]() -> T_InputInstrNode& {
+		if ( hasDefault ) {
+			return instructions.add< T_InputInstrNode >(
+					input[ 1 ] , input[ 2 ] );
+		}
+		return instructions.add< T_InputInstrNode >( input[ 1 ] );
+	})( ) );
+	instr.location( ) = input[ 0 ].location( );
+}
+
+/*----------------------------------------------------------------------------*/
+
+M_INSTR_( Pipeline )
 {
 	if ( input.size( ) < 3 ) {
 		errors.addNew( "identifier and program identifiers expected" ,
@@ -699,9 +722,7 @@ void T_ParserImpl_::parsePipelineInstruction(
 
 /*----------------------------------------------------------------------------*/
 
-void T_ParserImpl_::parseProfileInstruction(
-		T_InstrListNode& instructions ,
-		T_SRDList const& input ) noexcept
+M_INSTR_( Profile )
 {
 	const bool hasEnough( input.size( ) < 2 );
 	if ( hasEnough || !input[ 1 ].isText( ) ) {
@@ -720,9 +741,7 @@ void T_ParserImpl_::parseProfileInstruction(
 
 /*----------------------------------------------------------------------------*/
 
-void T_ParserImpl_::parseProgramInstruction(
-		T_InstrListNode& instructions ,
-		T_SRDList const& input ) noexcept
+M_INSTR_( Program )
 {
 	bool ok{ true };
 	if ( input.size( ) == 1 ) {
@@ -758,9 +777,7 @@ void T_ParserImpl_::parseProgramInstruction(
 
 /*----------------------------------------------------------------------------*/
 
-void T_ParserImpl_::parseSetInstruction(
-		T_InstrListNode& instructions ,
-		T_SRDList const& input ) noexcept
+M_INSTR_( Set )
 {
 	bool ok{ true };
 	if ( input.size( ) == 1 ) {
@@ -794,9 +811,7 @@ void T_ParserImpl_::parseSetInstruction(
 
 /*----------------------------------------------------------------------------*/
 
-void T_ParserImpl_::parseTextureInstruction(
-		T_InstrListNode& instructions ,
-		T_SRDList const& input ) noexcept
+M_INSTR_( Texture )
 {
 	if ( input.size( ) < 2 || input[ 1 ].type( ) != E_SRDTokenType::WORD ) {
 		errors.addNew( "texture identifier expected" ,
diff --git a/opast.hh b/opast.hh
index 3a6689c..bdf5016 100644
--- a/opast.hh
+++ b/opast.hh
@@ -25,6 +25,7 @@ class A_Node
 		//
 		OP_CALL ,	// Function call
 		OP_COND ,	// Conditional instruction
+		OP_INPUT ,	// Input declaration
 		OP_PIPELINE ,	// Shader pipeline declaration
 		OP_PROFILE ,	// Profiling block
 		OP_PROGRAM ,	// Shader program declaration
@@ -233,6 +234,7 @@ using P_ExpressionNode = T_OwnPtr< A_ExpressionNode >;
 
 /*============================================================================*/
 
+// Function call
 class T_CallInstrNode : public A_InstructionNode
 {
     private:
@@ -312,6 +314,41 @@ class T_CondInstrNode : public A_InstructionNode
 		{ return *defaultCase_; }
 };
 
+// Input declaration
+class T_InputInstrNode : public A_InstructionNode
+{
+    private:
+	T_String name_;
+	T_SRDLocation nameLocation_;
+	float defValue_;
+	T_SRDLocation dvLocation_;
+
+    public:
+	T_InputInstrNode( T_InstrListNode& parent ,
+			T_SRDToken const& tName ) noexcept
+		: A_InstructionNode( OP_INPUT , parent ) ,
+			name_( tName.stringValue( ) ) , nameLocation_( tName.location( ) )
+	{}
+
+	T_InputInstrNode( T_InstrListNode& parent ,
+			T_SRDToken const& tName ,
+			T_SRDToken const& tDefault ) noexcept
+		: A_InstructionNode( OP_INPUT , parent ) ,
+			name_( tName.stringValue( ) ) , nameLocation_( tName.location( ) ) ,
+			defValue_( tDefault.floatValue( ) ) , dvLocation_( tDefault.location( ) )
+	{}
+
+	T_String const& name( ) const noexcept
+		{ return name_; }
+	T_SRDLocation const& nameLocation( ) const noexcept
+		{ return nameLocation_; }
+
+	float defValue( ) const noexcept
+		{ return defValue_; }
+	T_SRDLocation const& defValueLocation( ) const noexcept
+		{ return dvLocation_; }
+};
+
 // Pipeline declaration instruction
 class T_PipelineInstrNode : public A_InstructionNode
 {