diff --git a/SPIRV/GlslangToSpv.cpp b/SPIRV/GlslangToSpv.cpp
index 50806d091..138a2cd25 100755
--- a/SPIRV/GlslangToSpv.cpp
+++ b/SPIRV/GlslangToSpv.cpp
@@ -122,6 +122,7 @@ protected:
     spv::Decoration TranslateAuxiliaryStorageDecoration(const glslang::TQualifier& qualifier);
     spv::BuiltIn TranslateBuiltInDecoration(glslang::TBuiltInVariable, bool memberDeclaration);
     spv::ImageFormat TranslateImageFormat(const glslang::TType& type);
+    spv::SelectionControlMask TranslateSelectionControl(glslang::TSelectionControl) const;
     spv::LoopControlMask TranslateLoopControl(glslang::TLoopControl) const;
     spv::StorageClass TranslateStorageClass(const glslang::TType&);
     spv::Id createSpvVariable(const glslang::TIntermSymbol*);
@@ -741,6 +742,16 @@ spv::ImageFormat TGlslangToSpvTraverser::TranslateImageFormat(const glslang::TTy
     }
 }
 
+spv::SelectionControlMask TGlslangToSpvTraverser::TranslateSelectionControl(glslang::TSelectionControl selectionControl) const
+{
+    switch (selectionControl) {
+    case glslang::ESelectionControlNone:        return spv::SelectionControlMaskNone;
+    case glslang::ESelectionControlFlatten:     return spv::SelectionControlFlattenMask;
+    case glslang::ESelectionControlDontFlatten: return spv::SelectionControlDontFlattenMask;
+    default:                                    return spv::SelectionControlMaskNone;
+    }
+}
+
 spv::LoopControlMask TGlslangToSpvTraverser::TranslateLoopControl(glslang::TLoopControl loopControl) const
 {
     switch (loopControl) {
@@ -1941,8 +1952,7 @@ bool TGlslangToSpvTraverser::visitSelection(glslang::TVisit /* visit */, glslang
         return false;
     }
 
-    // Instead, emit control flow...
-
+    // Instead, emit control flow...    
     // Don't handle results as temporaries, because there will be two names
     // and better to leave SSA to later passes.
     spv::Id result = (node->getBasicType() == glslang::EbtVoid)
@@ -1952,8 +1962,11 @@ bool TGlslangToSpvTraverser::visitSelection(glslang::TVisit /* visit */, glslang
     // emit the condition before doing anything with selection
     node->getCondition()->traverse(this);
 
+    // Selection control:
+    const spv::SelectionControlMask control = TranslateSelectionControl(node->getSelectionControl());
+
     // make an "if" based on the value created by the condition
-    spv::Builder::If ifBuilder(accessChainLoad(node->getCondition()->getType()), builder);
+    spv::Builder::If ifBuilder(accessChainLoad(node->getCondition()->getType()), control, builder);
 
     // emit the "then" statement
     if (node->getTrueBlock() != nullptr) {
@@ -1991,6 +2004,9 @@ bool TGlslangToSpvTraverser::visitSwitch(glslang::TVisit /* visit */, glslang::T
     node->getCondition()->traverse(this);
     spv::Id selector = accessChainLoad(node->getCondition()->getAsTyped()->getType());
 
+    // Selection control:
+    const spv::SelectionControlMask control = TranslateSelectionControl(node->getSelectionControl());
+
     // browse the children to sort out code segments
     int defaultSegment = -1;
     std::vector<TIntermNode*> codeSegments;
@@ -2016,7 +2032,7 @@ bool TGlslangToSpvTraverser::visitSwitch(glslang::TVisit /* visit */, glslang::T
 
     // make the switch statement
     std::vector<spv::Block*> segmentBlocks; // returned, as the blocks allocated in the call
-    builder.makeSwitch(selector, (int)codeSegments.size(), caseValues, valueIndexToSegment, defaultSegment, segmentBlocks);
+    builder.makeSwitch(selector, control, (int)codeSegments.size(), caseValues, valueIndexToSegment, defaultSegment, segmentBlocks);
 
     // emit all the code in the segments
     breakForLoop.push(false);
@@ -5707,7 +5723,7 @@ spv::Id TGlslangToSpvTraverser::createShortCircuit(glslang::TOperator op, glslan
         leftId = builder.createUnaryOp(spv::OpLogicalNot, boolTypeId, leftId);
 
     // make an "if" based on the left value
-    spv::Builder::If ifBuilder(leftId, builder);
+    spv::Builder::If ifBuilder(leftId, spv::SelectionControlMaskNone, builder);
 
     // emit right operand as the "then" part of the "if"
     builder.clearAccessChain();
diff --git a/SPIRV/SpvBuilder.cpp b/SPIRV/SpvBuilder.cpp
index ffd17af1b..11e9fe600 100644
--- a/SPIRV/SpvBuilder.cpp
+++ b/SPIRV/SpvBuilder.cpp
@@ -2009,9 +2009,10 @@ Id Builder::createMatrixConstructor(Decoration precision, const std::vector<Id>&
 }
 
 // Comments in header
-Builder::If::If(Id cond, Builder& gb) :
+Builder::If::If(Id cond, unsigned int ctrl, Builder& gb) :
     builder(gb),
     condition(cond),
+    control(ctrl),
     elseBlock(0)
 {
     function = &builder.getBuildPoint()->getParent();
@@ -2052,7 +2053,7 @@ void Builder::If::makeEndIf()
 
     // Go back to the headerBlock and make the flow control split
     builder.setBuildPoint(headerBlock);
-    builder.createSelectionMerge(mergeBlock, SelectionControlMaskNone);
+    builder.createSelectionMerge(mergeBlock, control);
     if (elseBlock)
         builder.createConditionalBranch(condition, thenBlock, elseBlock);
     else
@@ -2064,7 +2065,7 @@ void Builder::If::makeEndIf()
 }
 
 // Comments in header
-void Builder::makeSwitch(Id selector, int numSegments, const std::vector<int>& caseValues,
+void Builder::makeSwitch(Id selector, unsigned int control, int numSegments, const std::vector<int>& caseValues,
                          const std::vector<int>& valueIndexToSegment, int defaultSegment,
                          std::vector<Block*>& segmentBlocks)
 {
@@ -2077,7 +2078,7 @@ void Builder::makeSwitch(Id selector, int numSegments, const std::vector<int>& c
     Block* mergeBlock = new Block(getUniqueId(), function);
 
     // make and insert the switch's selection-merge instruction
-    createSelectionMerge(mergeBlock, SelectionControlMaskNone);
+    createSelectionMerge(mergeBlock, control);
 
     // make the switch instruction
     Instruction* switchInst = new Instruction(NoResult, NoType, OpSwitch);
diff --git a/SPIRV/SpvBuilder.h b/SPIRV/SpvBuilder.h
index 92f5084c1..2b17ba608 100755
--- a/SPIRV/SpvBuilder.h
+++ b/SPIRV/SpvBuilder.h
@@ -385,7 +385,7 @@ public:
     // Helper to use for building nested control flow with if-then-else.
     class If {
     public:
-        If(Id condition, Builder& builder);
+        If(Id condition, unsigned int ctrl, Builder& builder);
         ~If() {}
 
         void makeBeginElse();
@@ -397,6 +397,7 @@ public:
 
         Builder& builder;
         Id condition;
+        unsigned int control;
         Function* function;
         Block* headerBlock;
         Block* thenBlock;
@@ -416,7 +417,7 @@ public:
     // Returns the right set of basic blocks to start each code segment with, so that the caller's
     // recursion stack can hold the memory for it.
     //
-    void makeSwitch(Id condition, int numSegments, const std::vector<int>& caseValues,
+    void makeSwitch(Id condition, unsigned int control, int numSegments, const std::vector<int>& caseValues,
                     const std::vector<int>& valueToSegment, int defaultSegment, std::vector<Block*>& segmentBB); // return argument
 
     // Add a branch to the innermost switch's merge block.
diff --git a/SPIRV/doc.cpp b/SPIRV/doc.cpp
index 03097d0cb..fb0cc36ea 100755
--- a/SPIRV/doc.cpp
+++ b/SPIRV/doc.cpp
@@ -637,13 +637,15 @@ const char* SelectControlString(int cont)
     }
 }
 
-const int LoopControlCeiling = 2;
+const int LoopControlCeiling = 4;
 
 const char* LoopControlString(int cont)
 {
     switch (cont) {
     case 0:  return "Unroll";
     case 1:  return "DontUnroll";
+    case 2:  return "DependencyInfinite";
+    case 3:  return "DependencyLength";
 
     case LoopControlCeiling:
     default: return "Bad";
diff --git a/Test/baseResults/hlsl.attribute.frag.out b/Test/baseResults/hlsl.attribute.frag.out
index ccd7693f7..47fb67760 100755
--- a/Test/baseResults/hlsl.attribute.frag.out
+++ b/Test/baseResults/hlsl.attribute.frag.out
@@ -90,7 +90,7 @@ gl_FragCoord origin is upper left
 11(@PixelShaderFunction(vf4;):           2 Function None 9
        10(input):      8(ptr) FunctionParameter
               12:             Label
-                              SelectionMerge 16 None
+                              SelectionMerge 16 DontFlatten 
                               BranchConditional 14 15 16
               15:               Label
                                 Branch 16
diff --git a/Test/baseResults/hlsl.if.frag.out b/Test/baseResults/hlsl.if.frag.out
index 89e0bb1b8..eade928aa 100755
--- a/Test/baseResults/hlsl.if.frag.out
+++ b/Test/baseResults/hlsl.if.frag.out
@@ -319,7 +319,7 @@ gl_FragCoord origin is upper left
               48:    7(fvec4) Load 10(input)
               49:   16(bvec4) FOrdEqual 47 48
               50:    15(bool) All 49
-                              SelectionMerge 52 None
+                              SelectionMerge 52 Flatten 
                               BranchConditional 50 51 52
               51:               Label
               53:    7(fvec4)   Load 10(input)
diff --git a/Test/baseResults/hlsl.switch.frag.out b/Test/baseResults/hlsl.switch.frag.out
index 192e1b4ff..9cb52f115 100755
--- a/Test/baseResults/hlsl.switch.frag.out
+++ b/Test/baseResults/hlsl.switch.frag.out
@@ -399,7 +399,7 @@ gl_FragCoord origin is upper left
                                 Branch 25
               25:             Label
               36:      9(int) Load 13(c)
-                              SelectionMerge 40 None
+                              SelectionMerge 40 DontFlatten 
                               Switch 36 39 
                                      case 1: 37
                                      case 2: 38
diff --git a/Test/hlsl.switch.frag b/Test/hlsl.switch.frag
index 88239c2be..78ebfef34 100644
--- a/Test/hlsl.switch.frag
+++ b/Test/hlsl.switch.frag
@@ -18,7 +18,7 @@ float4 PixelShaderFunction(float4 input, int c, int d) : COLOR0
         break;
     }
 
-    switch (c) {
+    [branch] switch (c) {
     case 1:
         ++input;
         break;
diff --git a/glslang/Include/intermediate.h b/glslang/Include/intermediate.h
index 0fcac0b54..0922d125a 100644
--- a/glslang/Include/intermediate.h
+++ b/glslang/Include/intermediate.h
@@ -861,6 +861,15 @@ protected:
     TType type;
 };
 
+//
+// Selection control hints
+//
+enum TSelectionControl {
+    ESelectionControlNone,
+    ESelectionControlFlatten,
+    ESelectionControlDontFlatten,
+};
+
 //
 // Loop control hints
 //
@@ -1285,19 +1294,22 @@ protected:
 class TIntermSelection : public TIntermTyped {
 public:
     TIntermSelection(TIntermTyped* cond, TIntermNode* trueB, TIntermNode* falseB) :
-        TIntermTyped(EbtVoid), condition(cond), trueBlock(trueB), falseBlock(falseB) {}
+        TIntermTyped(EbtVoid), condition(cond), trueBlock(trueB), falseBlock(falseB), control(ESelectionControlNone) {}
     TIntermSelection(TIntermTyped* cond, TIntermNode* trueB, TIntermNode* falseB, const TType& type) :
-        TIntermTyped(type), condition(cond), trueBlock(trueB), falseBlock(falseB) {}
+        TIntermTyped(type), condition(cond), trueBlock(trueB), falseBlock(falseB), control(ESelectionControlNone) {}
     virtual void traverse(TIntermTraverser*);
     virtual TIntermTyped* getCondition() const { return condition; }
     virtual TIntermNode* getTrueBlock() const { return trueBlock; }
     virtual TIntermNode* getFalseBlock() const { return falseBlock; }
     virtual       TIntermSelection* getAsSelectionNode()       { return this; }
     virtual const TIntermSelection* getAsSelectionNode() const { return this; }
+    void setSelectionControl(TSelectionControl c) { control = c; }
+    TSelectionControl getSelectionControl() const { return control; }
 protected:
     TIntermTyped* condition;
     TIntermNode* trueBlock;
     TIntermNode* falseBlock;
+    TSelectionControl control;    // selection control hint
 };
 
 //
@@ -1308,15 +1320,18 @@ protected:
 //
 class TIntermSwitch : public TIntermNode {
 public:
-    TIntermSwitch(TIntermTyped* cond, TIntermAggregate* b) : condition(cond), body(b) { }
+    TIntermSwitch(TIntermTyped* cond, TIntermAggregate* b) : condition(cond), body(b), control(ESelectionControlNone) { }
     virtual void traverse(TIntermTraverser*);
     virtual TIntermNode* getCondition() const { return condition; }
     virtual TIntermAggregate* getBody() const { return body; }
     virtual       TIntermSwitch* getAsSwitchNode()       { return this; }
     virtual const TIntermSwitch* getAsSwitchNode() const { return this; }
+    void setSelectionControl(TSelectionControl c) { control = c; }
+    TSelectionControl getSelectionControl() const { return control; }
 protected:
     TIntermTyped* condition;
     TIntermAggregate* body;
+    TSelectionControl control;    // selection control hint
 };
 
 enum TVisit
diff --git a/glslang/MachineIndependent/Intermediate.cpp b/glslang/MachineIndependent/Intermediate.cpp
index a08944a5e..04a45e039 100644
--- a/glslang/MachineIndependent/Intermediate.cpp
+++ b/glslang/MachineIndependent/Intermediate.cpp
@@ -1614,7 +1614,7 @@ TIntermAggregate* TIntermediate::makeAggregate(const TSourceLoc& loc)
 //
 // Returns the selection node created.
 //
-TIntermTyped* TIntermediate::addSelection(TIntermTyped* cond, TIntermNodePair nodePair, const TSourceLoc& loc)
+TIntermTyped* TIntermediate::addSelection(TIntermTyped* cond, TIntermNodePair nodePair, const TSourceLoc& loc, TSelectionControl control)
 {
     //
     // Don't prune the false path for compile-time constants; it's needed
@@ -1623,6 +1623,7 @@ TIntermTyped* TIntermediate::addSelection(TIntermTyped* cond, TIntermNodePair no
 
     TIntermSelection* node = new TIntermSelection(cond, nodePair.node1, nodePair.node2);
     node->setLoc(loc);
+    node->setSelectionControl(control);
 
     return node;
 }
@@ -1665,12 +1666,12 @@ TIntermTyped* TIntermediate::addMethod(TIntermTyped* object, const TType& type,
 //
 // Returns the selection node created, or nullptr if one could not be.
 //
-TIntermTyped* TIntermediate::addSelection(TIntermTyped* cond, TIntermTyped* trueBlock, TIntermTyped* falseBlock, const TSourceLoc& loc)
+TIntermTyped* TIntermediate::addSelection(TIntermTyped* cond, TIntermTyped* trueBlock, TIntermTyped* falseBlock, const TSourceLoc& loc, TSelectionControl control)
 {
     // If it's void, go to the if-then-else selection()
     if (trueBlock->getBasicType() == EbtVoid && falseBlock->getBasicType() == EbtVoid) {
         TIntermNodePair pair = { trueBlock, falseBlock };
-        return addSelection(cond, pair, loc);
+        return addSelection(cond, pair, loc, control);
     }
 
     //
diff --git a/glslang/MachineIndependent/localintermediate.h b/glslang/MachineIndependent/localintermediate.h
index 4eacf58ca..c1daf1b50 100644
--- a/glslang/MachineIndependent/localintermediate.h
+++ b/glslang/MachineIndependent/localintermediate.h
@@ -276,8 +276,8 @@ public:
     TIntermAggregate* makeAggregate(const TSourceLoc&);
     TIntermTyped* setAggregateOperator(TIntermNode*, TOperator, const TType& type, TSourceLoc);
     bool areAllChildConst(TIntermAggregate* aggrNode);
-    TIntermTyped* addSelection(TIntermTyped* cond, TIntermNodePair code, const TSourceLoc&);
-    TIntermTyped* addSelection(TIntermTyped* cond, TIntermTyped* trueBlock, TIntermTyped* falseBlock, const TSourceLoc&);
+    TIntermTyped* addSelection(TIntermTyped* cond, TIntermNodePair code, const TSourceLoc&, TSelectionControl = ESelectionControlNone);
+    TIntermTyped* addSelection(TIntermTyped* cond, TIntermTyped* trueBlock, TIntermTyped* falseBlock, const TSourceLoc&, TSelectionControl = ESelectionControlNone);
     TIntermTyped* addComma(TIntermTyped* left, TIntermTyped* right, const TSourceLoc&);
     TIntermTyped* addMethod(TIntermTyped*, const TType&, const TString*, const TSourceLoc&);
     TIntermConstantUnion* addConstantUnion(const TConstUnionArray&, const TType&, const TSourceLoc&, bool literal = false) const;
diff --git a/hlsl/hlslGrammar.cpp b/hlsl/hlslGrammar.cpp
index a711fd338..95869e8d4 100755
--- a/hlsl/hlslGrammar.cpp
+++ b/hlsl/hlslGrammar.cpp
@@ -3201,10 +3201,10 @@ bool HlslGrammar::acceptStatement(TIntermNode*& statement)
         return acceptScopedCompoundStatement(statement);
 
     case EHTokIf:
-        return acceptSelectionStatement(statement);
+        return acceptSelectionStatement(statement, attributes);
 
     case EHTokSwitch:
-        return acceptSwitchStatement(statement);
+        return acceptSwitchStatement(statement, attributes);
 
     case EHTokFor:
     case EHTokDo:
@@ -3317,10 +3317,12 @@ void HlslGrammar::acceptAttributes(TAttributeMap& attributes)
 //      : IF LEFT_PAREN expression RIGHT_PAREN statement
 //      : IF LEFT_PAREN expression RIGHT_PAREN statement ELSE statement
 //
-bool HlslGrammar::acceptSelectionStatement(TIntermNode*& statement)
+bool HlslGrammar::acceptSelectionStatement(TIntermNode*& statement, const TAttributeMap& attributes)
 {
     TSourceLoc loc = token.loc;
 
+    const TSelectionControl control = parseContext.handleSelectionControl(attributes);
+
     // IF
     if (! acceptTokenClass(EHTokIf))
         return false;
@@ -3358,7 +3360,7 @@ bool HlslGrammar::acceptSelectionStatement(TIntermNode*& statement)
     }
 
     // Put the pieces together
-    statement = intermediate.addSelection(condition, thenElse, loc);
+    statement = intermediate.addSelection(condition, thenElse, loc, control);
     parseContext.popScope();
     --parseContext.controlFlowNestingLevel;
 
@@ -3368,10 +3370,13 @@ bool HlslGrammar::acceptSelectionStatement(TIntermNode*& statement)
 // switch_statement
 //      : SWITCH LEFT_PAREN expression RIGHT_PAREN compound_statement
 //
-bool HlslGrammar::acceptSwitchStatement(TIntermNode*& statement)
+bool HlslGrammar::acceptSwitchStatement(TIntermNode*& statement, const TAttributeMap& attributes)
 {
     // SWITCH
     TSourceLoc loc = token.loc;
+
+    const TSelectionControl control = parseContext.handleSelectionControl(attributes);
+
     if (! acceptTokenClass(EHTokSwitch))
         return false;
 
@@ -3391,7 +3396,7 @@ bool HlslGrammar::acceptSwitchStatement(TIntermNode*& statement)
     --parseContext.controlFlowNestingLevel;
 
     if (statementOkay)
-        statement = parseContext.addSwitch(loc, switchExpression, statement ? statement->getAsAggregate() : nullptr);
+        statement = parseContext.addSwitch(loc, switchExpression, statement ? statement->getAsAggregate() : nullptr, control);
 
     parseContext.popSwitchSequence();
     parseContext.popScope();
diff --git a/hlsl/hlslGrammar.h b/hlsl/hlslGrammar.h
index 5e56eddcc..ded8e9669 100755
--- a/hlsl/hlslGrammar.h
+++ b/hlsl/hlslGrammar.h
@@ -116,8 +116,8 @@ namespace glslang {
         bool acceptStatement(TIntermNode*&);
         bool acceptNestedStatement(TIntermNode*&);
         void acceptAttributes(TAttributeMap&);
-        bool acceptSelectionStatement(TIntermNode*&);
-        bool acceptSwitchStatement(TIntermNode*&);
+        bool acceptSelectionStatement(TIntermNode*&, const TAttributeMap&);
+        bool acceptSwitchStatement(TIntermNode*&, const TAttributeMap&);
         bool acceptIterationStatement(TIntermNode*&, const TAttributeMap&);
         bool acceptJumpStatement(TIntermNode*&);
         bool acceptCaseLabel(TIntermNode*&);
diff --git a/hlsl/hlslParseHelper.cpp b/hlsl/hlslParseHelper.cpp
index 1df7ba3c3..27dac886a 100755
--- a/hlsl/hlslParseHelper.cpp
+++ b/hlsl/hlslParseHelper.cpp
@@ -8273,6 +8273,19 @@ bool HlslParseContext::handleOutputGeometry(const TSourceLoc& loc, const TLayout
     return true;
 }
 
+//
+// Selection hints
+//
+TSelectionControl HlslParseContext::handleSelectionControl(const TAttributeMap& attributes) const
+{
+    if (attributes.contains(EatFlatten))
+        return ESelectionControlFlatten;
+    else if (attributes.contains(EatBranch))
+        return ESelectionControlDontFlatten;
+    else
+        return ESelectionControlNone;
+}
+
 //
 // Loop hints
 //
@@ -8286,7 +8299,6 @@ TLoopControl HlslParseContext::handleLoopControl(const TAttributeMap& attributes
         return ELoopControlNone;
 }
 
-
 //
 // Updating default qualifier for the case of a declaration with just a qualifier,
 // no type, block, or identifier.
@@ -8425,7 +8437,7 @@ void HlslParseContext::wrapupSwitchSubsequence(TIntermAggregate* statements, TIn
 // Turn the top-level node sequence built up of wrapupSwitchSubsequence
 // into a switch node.
 //
-TIntermNode* HlslParseContext::addSwitch(const TSourceLoc& loc, TIntermTyped* expression, TIntermAggregate* lastStatements)
+TIntermNode* HlslParseContext::addSwitch(const TSourceLoc& loc, TIntermTyped* expression, TIntermAggregate* lastStatements, TSelectionControl control)
 {
     wrapupSwitchSubsequence(lastStatements, nullptr);
 
@@ -8452,6 +8464,7 @@ TIntermNode* HlslParseContext::addSwitch(const TSourceLoc& loc, TIntermTyped* ex
 
     TIntermSwitch* switchNode = new TIntermSwitch(expression, body);
     switchNode->setLoc(loc);
+    switchNode->setSelectionControl(control);
 
     return switchNode;
 }
diff --git a/hlsl/hlslParseHelper.h b/hlsl/hlslParseHelper.h
index 15c7b0705..713e8303e 100755
--- a/hlsl/hlslParseHelper.h
+++ b/hlsl/hlslParseHelper.h
@@ -159,7 +159,7 @@ public:
     void addQualifierToExisting(const TSourceLoc&, TQualifier, TIdentifierList&);
     void updateStandaloneQualifierDefaults(const TSourceLoc&, const TPublicType&);
     void wrapupSwitchSubsequence(TIntermAggregate* statements, TIntermNode* branchNode);
-    TIntermNode* addSwitch(const TSourceLoc&, TIntermTyped* expression, TIntermAggregate* body);
+    TIntermNode* addSwitch(const TSourceLoc&, TIntermTyped* expression, TIntermAggregate* body, TSelectionControl control);
 
     void updateImplicitArraySize(const TSourceLoc&, TIntermNode*, int index);
 
@@ -198,6 +198,9 @@ public:
     bool handleOutputGeometry(const TSourceLoc&, const TLayoutGeometry& geometry);
     bool handleInputGeometry(const TSourceLoc&, const TLayoutGeometry& geometry);
 
+    // Determine selection control from attributes
+    TSelectionControl handleSelectionControl(const TAttributeMap& attributes) const;
+
     // Determine loop control from attributes
     TLoopControl handleLoopControl(const TAttributeMap& attributes) const;