diff --git a/csharp/ql/lib/semmle/code/csharp/Assignable.qll b/csharp/ql/lib/semmle/code/csharp/Assignable.qll
index 5cd9ee9ede0..d2df0a5a05e 100644
--- a/csharp/ql/lib/semmle/code/csharp/Assignable.qll
+++ b/csharp/ql/lib/semmle/code/csharp/Assignable.qll
@@ -271,6 +271,8 @@ module AssignableInternal {
     def = TPatternDefinition(result)
     or
     def = TAssignOperationDefinition(result)
+    or
+    def = TParameterDefaultDefinition(_, result)
   }
 
   /** A local variable declaration at the top-level of a pattern. */
@@ -308,10 +310,17 @@ module AssignableInternal {
         exists(Callable c | p = c.getAParameter() |
           c.hasBody()
           or
-          // Same as `c.(Constructor).hasInitializer()`, but avoids negative recursion warning
-          c.getAChildExpr() instanceof @constructor_init_expr
+          c.(Constructor).hasInitializer()
         )
       } or
+      TParameterDefaultDefinition(Parameter p, Expr default) {
+        exists(Callable c | p = c.getAParameter() |
+          c.hasBody()
+          or
+          c.(Constructor).hasInitializer()
+        ) and
+        default = p.getDefaultValue()
+      } or
       TAddressOfDefinition(AddressOfExpr aoe) or
       TPatternDefinition(TopLevelPatternDecl tlpd) or
       TAssignOperationDefinition(AssignOperation ao) {
@@ -350,6 +359,8 @@ module AssignableInternal {
         any(AssignableDefinitions::PatternDefinition pd | result = pd.getDeclaration().getVariable())
       or
       def = any(AssignableDefinitions::InitializerDefinition init | result = init.getAssignable())
+      or
+      def = TParameterDefaultDefinition(result, _)
     }
 
     // Not defined by dispatch in order to avoid too conservative negative recursion error
@@ -493,11 +504,6 @@ class AssignableDefinition extends TAssignableDefinition {
       exists(Ssa::ExplicitDefinition def | result = def.getAFirstReadAtNode(cfn) |
         this = def.getADefinition()
       )
-      or
-      exists(Ssa::ImplicitParameterDefinition def | result = def.getAFirstReadAtNode(cfn) |
-        this.(AssignableDefinitions::ImplicitParameterDefinition).getParameter() =
-          def.getParameter()
-      )
     )
   }
 
@@ -689,7 +695,33 @@ module AssignableDefinitions {
 
     override string toString() { result = p.toString() }
 
-    override Location getLocation() { result = this.getTarget().getLocation() }
+    override Location getLocation() { result = p.getLocation() }
+  }
+
+  /**
+   * A default value assigned to a parameter.
+   */
+  class ParameterDefaultDefinition extends AssignableDefinition, TParameterDefaultDefinition {
+    Parameter p;
+    Expr default;
+
+    ParameterDefaultDefinition() { this = TParameterDefaultDefinition(p, default) }
+
+    /** Gets the underlying parameter. */
+    Parameter getParameter() { result = p }
+
+    /** Gets the default value expression for the parameter. */
+    Expr getDefaultValue() { result = default }
+
+    override Expr getSource() { result = default }
+
+    override Expr getElement() { result = default }
+
+    override Callable getEnclosingCallable() { result = p.getCallable() }
+
+    override string toString() { result = p.toString() + " = ..." }
+
+    override Location getLocation() { result = default.getLocation() }
   }
 
   /**
diff --git a/csharp/ql/lib/semmle/code/csharp/controlflow/Guards.qll b/csharp/ql/lib/semmle/code/csharp/controlflow/Guards.qll
index 52de1c2fe0e..a8fe2e432e2 100644
--- a/csharp/ql/lib/semmle/code/csharp/controlflow/Guards.qll
+++ b/csharp/ql/lib/semmle/code/csharp/controlflow/Guards.qll
@@ -205,7 +205,7 @@ private module LogicInput implements GuardsImpl::LogicInputSig {
     }
   }
 
-  class SsaParameterInit extends SsaDefinition instanceof Ssa::ImplicitParameterDefinition {
+  class SsaParameterInit extends SsaDefinition instanceof Ssa::ParameterDefinition {
     Parameter getParameter() { result = super.getParameter() }
   }
 
diff --git a/csharp/ql/lib/semmle/code/csharp/dataflow/Nullness.qll b/csharp/ql/lib/semmle/code/csharp/dataflow/Nullness.qll
index d36fb68b915..14d343dedfb 100644
--- a/csharp/ql/lib/semmle/code/csharp/dataflow/Nullness.qll
+++ b/csharp/ql/lib/semmle/code/csharp/dataflow/Nullness.qll
@@ -130,7 +130,7 @@ private predicate dereferenceAt(ControlFlowNode node, Ssa::Definition def, Deref
   d = def.getAReadAtNode(node)
 }
 
-private predicate isMaybeNullArgument(Ssa::ImplicitParameterDefinition def, MaybeNullExpr arg) {
+private predicate isMaybeNullArgument(Ssa::ParameterDefinition def, MaybeNullExpr arg) {
   exists(AssignableDefinitions::ImplicitParameterDefinition pdef, Parameter p |
     p = def.getParameter()
   |
@@ -181,7 +181,7 @@ private predicate hasMultipleParamsArguments(Call c) {
   )
 }
 
-private predicate isNullDefaultArgument(Ssa::ImplicitParameterDefinition def, AlwaysNullExpr arg) {
+private predicate isNullDefaultArgument(Ssa::ParameterDefinition def, AlwaysNullExpr arg) {
   exists(AssignableDefinitions::ImplicitParameterDefinition pdef, Parameter p |
     p = def.getParameter()
   |
@@ -337,8 +337,7 @@ class Dereference extends G::DereferenceableExpr {
         or
         p.fromSource() and
         exists(
-          Ssa::ImplicitParameterDefinition def,
-          AssignableDefinitions::ImplicitParameterDefinition pdef
+          Ssa::ParameterDefinition def, AssignableDefinitions::ImplicitParameterDefinition pdef
         |
           p = def.getParameter()
         |
diff --git a/csharp/ql/lib/semmle/code/csharp/dataflow/SSA.qll b/csharp/ql/lib/semmle/code/csharp/dataflow/SSA.qll
index 92149e02640..8f5b04c6708 100644
--- a/csharp/ql/lib/semmle/code/csharp/dataflow/SSA.qll
+++ b/csharp/ql/lib/semmle/code/csharp/dataflow/SSA.qll
@@ -9,7 +9,6 @@ import csharp
  */
 module Ssa {
   private import internal.SsaImpl as SsaImpl
-  private import semmle.code.csharp.internal.Location
 
   pragma[nomagic]
   private predicate assignableDefinitionLocalScopeVariable(
@@ -19,15 +18,6 @@ module Ssa {
     ad.getEnclosingCallable() = c
   }
 
-  pragma[nomagic]
-  private predicate localScopeSourceVariable(
-    SourceVariables::LocalScopeSourceVariable sv, LocalScopeVariable v, Callable c1, Callable c2
-  ) {
-    sv.getAssignable() = v and
-    sv.getEnclosingCallable() = c1 and
-    v.getCallable() = c2
-  }
-
   /**
    * A variable that can be SSA converted.
    *
@@ -54,7 +44,7 @@ module Ssa {
       not exists(result.getTargetAccess()) and
       exists(LocalScopeVariable v, Callable c |
         assignableDefinitionLocalScopeVariable(result, v, c) and
-        localScopeSourceVariable(this, v, c, _)
+        SsaImpl::localScopeSourceVariable(this, v, c, _)
       )
     }
 
@@ -482,8 +472,8 @@ module Ssa {
 
   /**
    * An SSA definition representing the implicit initialization of a variable
-   * at the beginning of a callable. Either a parameter, a local scope variable
-   * captured by the callable, or a field or property accessed inside the callable.
+   * at the beginning of a callable. Either a local scope variable captured by
+   * the callable or a field or property accessed inside the callable.
    */
   class ImplicitEntryDefinition extends ImplicitDefinition {
     ImplicitEntryDefinition() {
@@ -507,51 +497,37 @@ module Ssa {
     override Location getLocation() { result = this.getCallable().getLocation() }
   }
 
-  private module NearestLocationInput implements NearestLocationInputSig {
-    class C = ImplicitParameterDefinition;
+  deprecated class ImplicitParameterDefinition = ParameterDefinition;
 
-    predicate relevantLocations(ImplicitParameterDefinition def, Location l1, Location l2) {
-      not def.getBasicBlock() instanceof EntryBasicBlock and
-      l1 = def.getParameter().getALocation() and
-      l2 = def.getBasicBlock().getLocation()
-    }
-  }
+  final class ParameterDefinition = SsaImpl::ParameterDefinitionImpl;
 
-  pragma[nomagic]
-  private predicate implicitEntryDef(ImplicitEntryDefinition def, SourceVariable v, Callable c) {
-    v = def.getSourceVariable() and
-    c = def.getCallable()
+  private class ExplicitParameterDefinition extends ExplicitDefinition,
+    SsaImpl::ParameterDefinitionImpl
+  {
+    private Parameter p;
+    override AssignableDefinitions::ImplicitParameterDefinition ad;
+
+    ExplicitParameterDefinition() { p = ad.getParameter() }
+
+    override Parameter getParameter() { result = p }
+
+    override string toString() { result = SsaImpl::ParameterDefinitionImpl.super.toString() }
   }
 
   /**
-   * An SSA definition representing the implicit initialization of a parameter
-   * at the beginning of a callable.
+   * An SSA definition representing the default value of a parameter.
    */
-  class ImplicitParameterDefinition extends ImplicitEntryDefinition {
+  class ParameterDefaultDefinition extends ExplicitDefinition {
     private Parameter p;
+    override AssignableDefinitions::ParameterDefaultDefinition ad;
 
-    ImplicitParameterDefinition() {
-      exists(SourceVariable sv, Callable c |
-        implicitEntryDef(this, sv, c) and
-        localScopeSourceVariable(sv, p, _, c)
-      )
-    }
+    ParameterDefaultDefinition() { p = ad.getParameter() }
 
     /** Gets the parameter that this entry definition represents. */
     Parameter getParameter() { result = p }
 
-    override Element getElement() { result = this.getParameter() }
-
     override string toString() {
-      result = "SSA param(" + pragma[only_bind_out](this.getParameter()) + ")"
-    }
-
-    override Location getLocation() {
-      not NearestLocation<NearestLocationInput>::nearestLocation(this, _, _) and
-      result = p.getLocation()
-      or
-      // multi-bodied method: use matching parameter location
-      NearestLocation<NearestLocationInput>::nearestLocation(this, result, _)
+      result = "SSA param_default(" + pragma[only_bind_out](this.getParameter()) + ")"
     }
   }
 
diff --git a/csharp/ql/lib/semmle/code/csharp/dataflow/internal/DataFlowPrivate.qll b/csharp/ql/lib/semmle/code/csharp/dataflow/internal/DataFlowPrivate.qll
index 1352f6e9f9f..c4d2a844103 100644
--- a/csharp/ql/lib/semmle/code/csharp/dataflow/internal/DataFlowPrivate.qll
+++ b/csharp/ql/lib/semmle/code/csharp/dataflow/internal/DataFlowPrivate.qll
@@ -1303,7 +1303,7 @@ private module NearestLocationInputParamAfterCallable implements NearestLocation
 
 private module ParameterNodes {
   pragma[nomagic]
-  private predicate ssaParamDef(Ssa::ImplicitParameterDefinition ssaDef, Parameter p, Location l) {
+  private predicate ssaParamDef(Ssa::ParameterDefinition ssaDef, Parameter p, Location l) {
     p = ssaDef.getParameter() and
     l = ssaDef.getLocation()
   }
@@ -1358,7 +1358,7 @@ private module ParameterNodes {
     }
 
     /** Gets the SSA definition corresponding to this parameter, if any. */
-    Ssa::ImplicitParameterDefinition getSsaDefinition() {
+    Ssa::ParameterDefinition getSsaDefinition() {
       exists(Parameter p, Location l |
         l = this.getParameterLocation(p) and
         ssaParamDef(result, p, l)
diff --git a/csharp/ql/lib/semmle/code/csharp/dataflow/internal/SsaImpl.qll b/csharp/ql/lib/semmle/code/csharp/dataflow/internal/SsaImpl.qll
index b2c44598524..b3a95977be9 100644
--- a/csharp/ql/lib/semmle/code/csharp/dataflow/internal/SsaImpl.qll
+++ b/csharp/ql/lib/semmle/code/csharp/dataflow/internal/SsaImpl.qll
@@ -7,6 +7,7 @@ private import codeql.ssa.Ssa as SsaImplCommon
 private import AssignableDefinitions
 private import semmle.code.csharp.controlflow.Guards as Guards
 private import semmle.code.csharp.dataflow.internal.BaseSSA
+private import semmle.code.csharp.internal.Location
 
 private module SsaInput implements SsaImplCommon::InputSig<Location, BasicBlock> {
   class SourceVariable = Ssa::SourceVariable;
@@ -126,7 +127,6 @@ private module SourceVariableImpl {
    */
   predicate variableDefinition(BasicBlock bb, int i, Ssa::SourceVariable v, AssignableDefinition ad) {
     ad = v.getADefinition() and
-    ad.getExpr().getControlFlowNode() = bb.getNode(i) and
     // In cases like `(x, x) = (0, 1)`, we discard the first (dead) definition of `x`
     not exists(TupleAssignmentDefinition first, TupleAssignmentDefinition second | first = ad |
       second.getAssignment() = first.getAssignment() and
@@ -136,7 +136,13 @@ private module SourceVariableImpl {
     // In cases like `M(out x, out x)`, there is no inherent evaluation order, so we
     // collapse the two definitions of `x`, using the first access as the representative,
     // and expose both definitions in `ExplicitDefinition.getADefinition()`
-    not ad = getASameOutRefDefAfter(v, _)
+    not ad = getASameOutRefDefAfter(v, _) and
+    (
+      ad.getExpr().getControlFlowNode() = bb.getNode(i)
+      or
+      ad.(AssignableDefinitions::ImplicitParameterDefinition).getParameter().getControlFlowNode() =
+        bb.getNode(i)
+    )
   }
 
   /**
@@ -243,6 +249,15 @@ private module SourceVariableImpl {
 private import SourceVariableImpl
 private import Ssa::SourceVariables
 
+pragma[nomagic]
+predicate localScopeSourceVariable(
+  Ssa::SourceVariables::LocalScopeSourceVariable sv, LocalScopeVariable v, Callable c1, Callable c2
+) {
+  sv.getAssignable() = v and
+  sv.getEnclosingCallable() = c1 and
+  v.getCallable() = c2
+}
+
 private module CallGraph {
   private import semmle.code.csharp.dispatch.Dispatch
 
@@ -767,9 +782,10 @@ private module Cached {
         v instanceof PlainFieldOrPropSourceVariable
       )
       or
-      // In case `c` has multiple bodies, we want each body to get its own implicit
-      // entry definition, so we use the basic block containing the body instead of
-      // the entry block.
+      // In case `c` has multiple bodies, we want each body to get its own set of
+      // parameter definitions, so we add special writes to the start of the basic
+      // blocks containing the bodies
+      strictcount(c.getBody()) > 1 and
       v.getAssignable() instanceof Parameter and
       bb.getANode().isBefore(c.getBody())
     )
@@ -962,7 +978,7 @@ private module DataFlowIntegrationInput implements Impl::DataFlowIntegrationInpu
   predicate ssaDefHasSource(WriteDefinition def) {
     // exclude flow directly from RHS to SSA definition, as we instead want to
     // go from RHS to matching assignable definition, and from there to SSA definition
-    def instanceof Ssa::ImplicitParameterDefinition
+    def instanceof Ssa::ParameterDefinition
   }
 
   /**
@@ -994,3 +1010,56 @@ private module DataFlowIntegrationInput implements Impl::DataFlowIntegrationInpu
 }
 
 private module DataFlowIntegrationImpl = Impl::DataFlowIntegration<DataFlowIntegrationInput>;
+
+private module MultiBodyNearestLocationInput implements NearestLocationInputSig {
+  class C = MultiBodyParameterDefinition;
+
+  predicate relevantLocations(MultiBodyParameterDefinition def, Location l1, Location l2) {
+    exists(Callable c, ControlFlowNode n |
+      l1 = def.getParameter().getALocation() and
+      n = def.getBasicBlock().getANode() and
+      n.isBefore(c.getBody()) and
+      l2 = n.getLocation()
+    )
+  }
+}
+
+pragma[nomagic]
+private predicate implicitEntryDef(
+  Ssa::ImplicitEntryDefinition def, Ssa::SourceVariable v, Callable c
+) {
+  v = def.getSourceVariable() and
+  c = def.getCallable()
+}
+
+/**
+ * An SSA definition representing the implicit initialization of a parameter
+ * at the beginning of a callable.
+ */
+abstract class ParameterDefinitionImpl extends Ssa::Definition {
+  /** Gets the parameter that this definition represents. */
+  abstract Parameter getParameter();
+
+  override string toString() {
+    result = "SSA param(" + pragma[only_bind_out](this.getParameter()) + ")"
+  }
+}
+
+class MultiBodyParameterDefinition extends ParameterDefinitionImpl, Ssa::ImplicitEntryDefinition {
+  private Parameter p;
+
+  MultiBodyParameterDefinition() {
+    exists(Ssa::SourceVariable sv, Callable c |
+      implicitEntryDef(this, sv, c) and
+      localScopeSourceVariable(sv, p, _, c)
+    )
+  }
+
+  override Parameter getParameter() { result = p }
+
+  override string toString() { result = ParameterDefinitionImpl.super.toString() }
+
+  override Location getLocation() {
+    NearestLocation<MultiBodyNearestLocationInput>::nearestLocation(this, result, _)
+  }
+}
diff --git a/csharp/ql/test/library-tests/csharp7/DefUse.ql b/csharp/ql/test/library-tests/csharp7/DefUse.ql
index a37b867e086..5957c009260 100644
--- a/csharp/ql/test/library-tests/csharp7/DefUse.ql
+++ b/csharp/ql/test/library-tests/csharp7/DefUse.ql
@@ -6,7 +6,7 @@ where
   (
     ult.(Ssa::ExplicitDefinition).getADefinition() = def
     or
-    ult.(Ssa::ImplicitParameterDefinition).getParameter() =
+    ult.(Ssa::ParameterDefinition).getParameter() =
       def.(AssignableDefinitions::ImplicitParameterDefinition).getParameter()
   ) and
   read = ssaDef.getARead()
diff --git a/csharp/ql/test/library-tests/dataflow/defuse/parameterUseEquivalence.ql b/csharp/ql/test/library-tests/dataflow/defuse/parameterUseEquivalence.ql
index e4216f89942..896092718a0 100644
--- a/csharp/ql/test/library-tests/dataflow/defuse/parameterUseEquivalence.ql
+++ b/csharp/ql/test/library-tests/dataflow/defuse/parameterUseEquivalence.ql
@@ -24,8 +24,7 @@ private LocalScopeVariableRead getAReachableUncertainRead(
   AssignableDefinitions::ImplicitParameterDefinition p
 ) {
   exists(Ssa::Definition ssaDef |
-    p.getParameter() =
-      ssaDef.getAnUltimateDefinition().(Ssa::ImplicitParameterDefinition).getParameter()
+    p.getParameter() = ssaDef.getAnUltimateDefinition().(Ssa::ParameterDefinition).getParameter()
   |
     result = ssaDef.getARead()
   )
diff --git a/csharp/ql/test/library-tests/dataflow/local/DataFlow.expected b/csharp/ql/test/library-tests/dataflow/local/DataFlow.expected
index ed80fa1e8b3..ef002f0396f 100644
--- a/csharp/ql/test/library-tests/dataflow/local/DataFlow.expected
+++ b/csharp/ql/test/library-tests/dataflow/local/DataFlow.expected
@@ -5,6 +5,7 @@
 | LocalDataFlow.cs:315:15:315:20 | access to local variable sink73 |
 | LocalDataFlow.cs:316:15:316:20 | access to local variable sink74 |
 | LocalDataFlow.cs:342:15:342:21 | access to parameter tainted |
+| LocalDataFlow.cs:387:15:387:15 | access to parameter s |
 | SSA.cs:9:15:9:22 | access to local variable ssaSink0 |
 | SSA.cs:25:15:25:22 | access to local variable ssaSink1 |
 | SSA.cs:43:15:43:22 | access to local variable ssaSink2 |
diff --git a/csharp/ql/test/library-tests/dataflow/local/DataFlowStep.expected b/csharp/ql/test/library-tests/dataflow/local/DataFlowStep.expected
index a22e56b0dd8..d1df5b77de0 100644
--- a/csharp/ql/test/library-tests/dataflow/local/DataFlowStep.expected
+++ b/csharp/ql/test/library-tests/dataflow/local/DataFlowStep.expected
@@ -529,6 +529,9 @@
 | LocalDataFlow.cs:381:17:381:29 | "not tainted" | LocalDataFlow.cs:381:13:381:13 | access to local variable x |
 | LocalDataFlow.cs:385:34:385:34 | SSA param(s) | LocalDataFlow.cs:387:15:387:15 | access to parameter s |
 | LocalDataFlow.cs:385:34:385:34 | s | LocalDataFlow.cs:385:34:385:34 | SSA param(s) |
+| LocalDataFlow.cs:385:38:385:51 | "taint source" | LocalDataFlow.cs:385:38:385:51 | s = ... |
+| LocalDataFlow.cs:385:38:385:51 | SSA param_default(s) | LocalDataFlow.cs:387:15:387:15 | access to parameter s |
+| LocalDataFlow.cs:385:38:385:51 | s = ... | LocalDataFlow.cs:385:38:385:51 | SSA param_default(s) |
 | SSA.cs:3:14:3:16 | this | SSA.cs:3:14:3:16 | this access |
 | SSA.cs:5:17:5:17 | SSA entry def(this.S) | SSA.cs:67:9:67:14 | access to field S |
 | SSA.cs:5:17:5:17 | this | SSA.cs:67:9:67:12 | this access |
diff --git a/csharp/ql/test/library-tests/dataflow/local/TaintTracking.expected b/csharp/ql/test/library-tests/dataflow/local/TaintTracking.expected
index 372d0bfb3e1..a7ba919f2d7 100644
--- a/csharp/ql/test/library-tests/dataflow/local/TaintTracking.expected
+++ b/csharp/ql/test/library-tests/dataflow/local/TaintTracking.expected
@@ -43,6 +43,7 @@
 | LocalDataFlow.cs:315:15:315:20 | access to local variable sink73 |
 | LocalDataFlow.cs:316:15:316:20 | access to local variable sink74 |
 | LocalDataFlow.cs:342:15:342:21 | access to parameter tainted |
+| LocalDataFlow.cs:387:15:387:15 | access to parameter s |
 | SSA.cs:9:15:9:22 | access to local variable ssaSink0 |
 | SSA.cs:25:15:25:22 | access to local variable ssaSink1 |
 | SSA.cs:43:15:43:22 | access to local variable ssaSink2 |
diff --git a/csharp/ql/test/library-tests/dataflow/local/TaintTrackingStep.expected b/csharp/ql/test/library-tests/dataflow/local/TaintTrackingStep.expected
index 87cd14bd25b..06251245a05 100644
--- a/csharp/ql/test/library-tests/dataflow/local/TaintTrackingStep.expected
+++ b/csharp/ql/test/library-tests/dataflow/local/TaintTrackingStep.expected
@@ -641,6 +641,9 @@
 | LocalDataFlow.cs:381:17:381:29 | "not tainted" | LocalDataFlow.cs:381:13:381:13 | access to local variable x |
 | LocalDataFlow.cs:385:34:385:34 | SSA param(s) | LocalDataFlow.cs:387:15:387:15 | access to parameter s |
 | LocalDataFlow.cs:385:34:385:34 | s | LocalDataFlow.cs:385:34:385:34 | SSA param(s) |
+| LocalDataFlow.cs:385:38:385:51 | "taint source" | LocalDataFlow.cs:385:38:385:51 | s = ... |
+| LocalDataFlow.cs:385:38:385:51 | SSA param_default(s) | LocalDataFlow.cs:387:15:387:15 | access to parameter s |
+| LocalDataFlow.cs:385:38:385:51 | s = ... | LocalDataFlow.cs:385:38:385:51 | SSA param_default(s) |
 | SSA.cs:3:14:3:16 | this | SSA.cs:3:14:3:16 | this access |
 | SSA.cs:5:17:5:17 | SSA entry def(this.S) | SSA.cs:67:9:67:14 | access to field S |
 | SSA.cs:5:17:5:17 | this | SSA.cs:67:9:67:12 | this access |
diff --git a/csharp/ql/test/library-tests/dataflow/ssa/BaseSsaConsistency.ql b/csharp/ql/test/library-tests/dataflow/ssa/BaseSsaConsistency.ql
index 4748f516114..d68e39fb396 100644
--- a/csharp/ql/test/library-tests/dataflow/ssa/BaseSsaConsistency.ql
+++ b/csharp/ql/test/library-tests/dataflow/ssa/BaseSsaConsistency.ql
@@ -12,7 +12,7 @@ where
     edef.getADefinition() = def and
     edef.getARead() = ar
   ) and
-  not exists(Ssa::ImplicitParameterDefinition edef |
+  not exists(Ssa::ParameterDefinition edef |
     edef.getParameter() = def.(AssignableDefinitions::ImplicitParameterDefinition).getParameter() and
     edef.getARead() = ar
   )
diff --git a/csharp/ql/test/library-tests/dataflow/ssa/DefAdjacentRead.expected b/csharp/ql/test/library-tests/dataflow/ssa/DefAdjacentRead.expected
index a6833b789f7..0350c73ce25 100644
--- a/csharp/ql/test/library-tests/dataflow/ssa/DefAdjacentRead.expected
+++ b/csharp/ql/test/library-tests/dataflow/ssa/DefAdjacentRead.expected
@@ -62,8 +62,6 @@
 | DefUse.cs:171:23:171:23 | a | DefUse.cs:171:23:180:9 | Action a = ... | DefUse.cs:181:9:181:9 | access to local variable a |
 | DefUse.cs:171:23:171:23 | a | DefUse.cs:186:9:190:9 | ... = ... | DefUse.cs:191:9:191:9 | access to local variable a |
 | DefaultParam.cs:3:20:3:20 | b | DefaultParam.cs:3:20:3:20 | b | DefaultParam.cs:5:16:5:16 | access to parameter b |
-| DefaultParam.cs:3:30:3:30 | s | DefaultParam.cs:3:30:3:30 | s | DefaultParam.cs:5:20:5:20 | access to parameter s |
-| DefaultParam.cs:3:42:3:42 | i | DefaultParam.cs:3:42:3:42 | i | DefaultParam.cs:5:24:5:24 | access to parameter i |
 | Example.cs:4:9:4:13 | Field | Example.cs:8:9:8:22 | ... = ... | Example.cs:9:13:9:22 | access to field Field |
 | Example.cs:6:23:6:23 | i | Example.cs:6:23:6:23 | i | Example.cs:8:22:8:22 | access to parameter i |
 | Example.cs:18:16:18:16 | p | Example.cs:18:16:18:16 | p | Example.cs:22:17:22:17 | access to parameter p |
@@ -85,8 +83,6 @@
 | Fields.cs:93:19:93:23 | Field | Fields.cs:102:9:102:28 | ... = ... | Fields.cs:104:16:104:25 | access to field Field |
 | Fields.cs:95:19:95:19 | f | Fields.cs:95:19:95:19 | f | Fields.cs:97:9:97:9 | access to parameter f |
 | Fields.cs:107:33:107:33 | f | Fields.cs:107:33:107:33 | f | Fields.cs:107:38:107:38 | access to parameter f |
-| MultiImplementationA.cs:5:22:5:22 | x | MultiImplementationA.cs:5:22:5:22 | x | MultiImplementationA.cs:5:28:5:28 | access to parameter x |
-| MultiImplementationA.cs:5:22:5:22 | x | MultiImplementationA.cs:5:22:5:22 | x | MultiImplementationB.cs:3:28:3:28 | access to parameter x |
 | OutRef.cs:5:9:5:13 | Field | OutRef.cs:13:28:13:32 | access to field Field | OutRef.cs:15:13:15:17 | access to field Field |
 | OutRef.cs:5:9:5:13 | Field | OutRef.cs:16:21:16:25 | access to field Field | OutRef.cs:17:13:17:17 | access to field Field |
 | OutRef.cs:5:9:5:13 | Field | OutRef.cs:16:32:16:36 | access to field Field | OutRef.cs:17:13:17:17 | access to field Field |
diff --git a/csharp/ql/test/library-tests/dataflow/ssa/SSAPhi.expected b/csharp/ql/test/library-tests/dataflow/ssa/SSAPhi.expected
index 1acf66efd96..7ace8cd316d 100644
--- a/csharp/ql/test/library-tests/dataflow/ssa/SSAPhi.expected
+++ b/csharp/ql/test/library-tests/dataflow/ssa/SSAPhi.expected
@@ -8,6 +8,10 @@
 | DefUse.cs:79:13:79:14 | x1 | DefUse.cs:80:9:80:51 | SSA phi(x1) | DefUse.cs:80:30:80:31 | SSA def(x1) |
 | DefUse.cs:97:13:97:14 | x5 | DefUse.cs:98:9:102:9 | SSA phi(x5) | DefUse.cs:97:13:97:18 | SSA def(x5) |
 | DefUse.cs:97:13:97:14 | x5 | DefUse.cs:98:9:102:9 | SSA phi(x5) | DefUse.cs:101:13:101:23 | SSA def(x5) |
+| DefaultParam.cs:3:30:3:30 | s | DefaultParam.cs:3:42:3:42 | SSA phi(s) | DefaultParam.cs:3:30:3:30 | SSA param(s) |
+| DefaultParam.cs:3:30:3:30 | s | DefaultParam.cs:3:42:3:42 | SSA phi(s) | DefaultParam.cs:3:34:3:35 | SSA param_default(s) |
+| DefaultParam.cs:3:42:3:42 | i | DefaultParam.cs:4:5:6:5 | SSA phi(i) | DefaultParam.cs:3:42:3:42 | SSA param(i) |
+| DefaultParam.cs:3:42:3:42 | i | DefaultParam.cs:4:5:6:5 | SSA phi(i) | DefaultParam.cs:3:46:3:46 | SSA param_default(i) |
 | Example.cs:8:9:8:18 | this.Field | Example.cs:10:9:13:24 | SSA phi(this.Field) | Example.cs:11:13:11:30 | SSA def(this.Field) |
 | Example.cs:8:9:8:18 | this.Field | Example.cs:10:9:13:24 | SSA phi(this.Field) | Example.cs:12:14:13:24 | SSA phi(this.Field) |
 | Example.cs:8:9:8:18 | this.Field | Example.cs:12:14:13:24 | SSA phi(this.Field) | Example.cs:8:9:8:22 | SSA def(this.Field) |
diff --git a/csharp/ql/test/library-tests/dataflow/ssa/SsaDef.expected b/csharp/ql/test/library-tests/dataflow/ssa/SsaDef.expected
index 8f4af9a3aac..507ff8b2b6e 100644
--- a/csharp/ql/test/library-tests/dataflow/ssa/SsaDef.expected
+++ b/csharp/ql/test/library-tests/dataflow/ssa/SsaDef.expected
@@ -95,7 +95,11 @@
 | DefUse.cs:188:13:188:18 | this.Field5 | DefUse.cs:188:13:188:22 | SSA def(this.Field5) |
 | DefaultParam.cs:3:20:3:20 | b | DefaultParam.cs:3:20:3:20 | SSA param(b) |
 | DefaultParam.cs:3:30:3:30 | s | DefaultParam.cs:3:30:3:30 | SSA param(s) |
+| DefaultParam.cs:3:30:3:30 | s | DefaultParam.cs:3:34:3:35 | SSA param_default(s) |
+| DefaultParam.cs:3:30:3:30 | s | DefaultParam.cs:3:42:3:42 | SSA phi(s) |
 | DefaultParam.cs:3:42:3:42 | i | DefaultParam.cs:3:42:3:42 | SSA param(i) |
+| DefaultParam.cs:3:42:3:42 | i | DefaultParam.cs:3:46:3:46 | SSA param_default(i) |
+| DefaultParam.cs:3:42:3:42 | i | DefaultParam.cs:4:5:6:5 | SSA phi(i) |
 | Example.cs:6:23:6:23 | i | Example.cs:6:23:6:23 | SSA param(i) |
 | Example.cs:8:9:8:18 | this.Field | Example.cs:8:9:8:22 | SSA def(this.Field) |
 | Example.cs:8:9:8:18 | this.Field | Example.cs:10:9:13:24 | SSA phi(this.Field) |
diff --git a/csharp/ql/test/library-tests/dataflow/ssa/SsaDefElement.expected b/csharp/ql/test/library-tests/dataflow/ssa/SsaDefElement.expected
index d0e2984050d..b6e2beaae69 100644
--- a/csharp/ql/test/library-tests/dataflow/ssa/SsaDefElement.expected
+++ b/csharp/ql/test/library-tests/dataflow/ssa/SsaDefElement.expected
@@ -90,7 +90,11 @@
 | DefUse.cs:191:9:191:11 | SSA call def(this.Field5) | DefUse.cs:191:9:191:11 | delegate call |
 | DefaultParam.cs:3:20:3:20 | SSA param(b) | DefaultParam.cs:3:20:3:20 | b |
 | DefaultParam.cs:3:30:3:30 | SSA param(s) | DefaultParam.cs:3:30:3:30 | s |
+| DefaultParam.cs:3:34:3:35 | SSA param_default(s) | DefaultParam.cs:3:34:3:35 | "" |
 | DefaultParam.cs:3:42:3:42 | SSA param(i) | DefaultParam.cs:3:42:3:42 | i |
+| DefaultParam.cs:3:42:3:42 | SSA phi(s) | DefaultParam.cs:3:42:3:42 | i |
+| DefaultParam.cs:3:46:3:46 | SSA param_default(i) | DefaultParam.cs:3:46:3:46 | 0 |
+| DefaultParam.cs:4:5:6:5 | SSA phi(i) | DefaultParam.cs:4:5:6:5 | {...} |
 | Example.cs:6:23:6:23 | SSA param(i) | Example.cs:6:23:6:23 | i |
 | Example.cs:8:9:8:22 | SSA def(this.Field) | Example.cs:8:9:8:22 | ... = ... |
 | Example.cs:11:13:11:30 | SSA def(this.Field) | Example.cs:11:13:11:30 | ... = ... |
@@ -148,8 +152,8 @@
 | Fields.cs:114:9:114:22 | SSA call def(this.Field) | Fields.cs:114:9:114:22 | call to method SetField |
 | Fields.cs:114:9:114:22 | SSA call def(this.Field.Field) | Fields.cs:114:9:114:22 | call to method SetField |
 | Fields.cs:114:9:114:22 | SSA qualifier def(this.Field.Field.xs) | Fields.cs:114:9:114:22 | call to method SetField |
-| MultiImplementationA.cs:5:22:5:22 | SSA param(x) | MultiImplementationA.cs:5:22:5:22 | x |
-| MultiImplementationB.cs:3:22:3:22 | SSA param(x) | MultiImplementationA.cs:5:22:5:22 | x |
+| MultiImplementationA.cs:5:22:5:22 | SSA param(x) | MultiImplementationA.cs:5:16:5:16 | M |
+| MultiImplementationB.cs:3:22:3:22 | SSA param(x) | MultiImplementationA.cs:5:16:5:16 | M |
 | OutRef.cs:7:10:7:10 | SSA entry def(this.Field) | OutRef.cs:7:10:7:10 | M |
 | OutRef.cs:9:13:9:17 | SSA def(j) | OutRef.cs:9:13:9:17 | Int32 j = ... |
 | OutRef.cs:10:25:10:25 | SSA def(i) | OutRef.cs:10:9:10:33 | call to method OutRefM |
diff --git a/csharp/ql/test/library-tests/dataflow/ssa/SsaExplicitDef.expected b/csharp/ql/test/library-tests/dataflow/ssa/SsaExplicitDef.expected
index 8582dd1cf6e..9a2e5c49b15 100644
--- a/csharp/ql/test/library-tests/dataflow/ssa/SsaExplicitDef.expected
+++ b/csharp/ql/test/library-tests/dataflow/ssa/SsaExplicitDef.expected
@@ -3,10 +3,18 @@
 | Capture.cs:19:20:19:20 | b | Capture.cs:19:20:23:13 | SSA def(b) | Capture.cs:19:20:23:13 | Action b = ... |
 | Capture.cs:30:16:30:16 | c | Capture.cs:30:16:30:35 | SSA def(c) | Capture.cs:30:16:30:35 | Action c = ... |
 | Capture.cs:52:16:52:16 | b | Capture.cs:52:16:52:43 | SSA def(b) | Capture.cs:52:16:52:43 | Action b = ... |
+| Capture.cs:57:57:57:63 | strings | Capture.cs:57:57:57:63 | SSA param(strings) | Capture.cs:57:57:57:63 | strings |
 | Capture.cs:60:27:60:27 | e | Capture.cs:60:27:60:38 | SSA def(e) | Capture.cs:60:27:60:38 | Func<String,Int32> e = ... |
+| Capture.cs:65:45:65:51 | strings | Capture.cs:65:45:65:51 | SSA param(strings) | Capture.cs:65:45:65:51 | strings |
+| Capture.cs:68:32:68:32 | s | Capture.cs:68:32:68:32 | SSA param(s) | Capture.cs:68:32:68:32 | s |
+| Capture.cs:69:25:69:25 | s | Capture.cs:69:25:69:25 | SSA param(s) | Capture.cs:69:25:69:25 | s |
+| Capture.cs:73:67:73:73 | strings | Capture.cs:73:67:73:73 | SSA param(strings) | Capture.cs:73:67:73:73 | strings |
 | Capture.cs:76:63:76:63 | e | Capture.cs:76:63:76:81 | SSA def(e) | Capture.cs:76:63:76:81 | Expression<Func<String,Int32>> e = ... |
+| Capture.cs:81:28:81:28 | i | Capture.cs:81:28:81:28 | SSA param(i) | Capture.cs:81:28:81:28 | i |
 | Capture.cs:81:28:81:28 | i | Capture.cs:81:34:81:36 | SSA def(i) | Capture.cs:81:34:81:36 | ...++ |
+| Capture.cs:83:65:83:71 | strings | Capture.cs:83:65:83:71 | SSA param(strings) | Capture.cs:83:65:83:71 | strings |
 | Capture.cs:86:64:86:64 | e | Capture.cs:86:64:86:73 | SSA def(e) | Capture.cs:86:64:86:73 | Expression<Func<String,Boolean>> e = ... |
+| Capture.cs:92:18:92:18 | d | Capture.cs:92:18:92:18 | SSA param(d) | Capture.cs:92:18:92:18 | d |
 | Capture.cs:98:17:98:17 | x | Capture.cs:98:17:98:21 | SSA def(x) | Capture.cs:98:17:98:21 | Int32 x = ... |
 | Capture.cs:117:17:117:17 | x | Capture.cs:117:17:117:21 | SSA def(x) | Capture.cs:117:17:117:21 | Int32 x = ... |
 | Capture.cs:198:28:198:29 | eh | Capture.cs:198:28:198:44 | SSA def(eh) | Capture.cs:198:28:198:44 | MyEventHandler eh = ... |
@@ -14,13 +22,18 @@
 | Capture.cs:210:24:210:24 | p | Capture.cs:210:24:210:59 | SSA def(p) | Capture.cs:210:24:210:59 | Process p = ... |
 | Capture.cs:212:30:212:35 | exited | Capture.cs:212:30:212:71 | SSA def(exited) | Capture.cs:212:30:212:71 | EventHandler exited = ... |
 | Capture.cs:248:36:248:36 | j | Capture.cs:251:13:251:17 | SSA def(j) | Capture.cs:251:13:251:17 | ... = ... |
+| Consistency.cs:7:25:7:25 | b | Consistency.cs:7:25:7:25 | SSA param(b) | Consistency.cs:7:25:7:25 | b |
 | Consistency.cs:15:17:15:17 | i | Consistency.cs:15:17:15:21 | SSA def(i) | Consistency.cs:15:17:15:21 | Int32 i = ... |
 | Consistency.cs:25:29:25:29 | c | Consistency.cs:25:29:25:29 | SSA def(c) | Consistency.cs:25:29:25:29 | Consistency c |
 | Consistency.cs:30:30:30:30 | c | Consistency.cs:32:9:32:29 | SSA def(c) | Consistency.cs:32:9:32:29 | ... = ... |
 | Consistency.cs:44:11:44:11 | s | Consistency.cs:44:11:44:11 | SSA def(s) | Consistency.cs:44:11:44:11 | S s |
+| Consistency.cs:49:30:49:30 | a | Consistency.cs:49:30:49:30 | SSA param(a) | Consistency.cs:49:30:49:30 | a |
+| Consistency.cs:49:37:49:37 | i | Consistency.cs:49:37:49:37 | SSA param(i) | Consistency.cs:49:37:49:37 | i |
+| Consistency.cs:51:20:51:20 | a | Consistency.cs:51:20:51:20 | SSA param(a) | Consistency.cs:51:20:51:20 | a |
 | Consistency.cs:56:17:56:17 | k | Consistency.cs:56:17:56:40 | SSA def(k) | Consistency.cs:56:17:56:40 | Int32 k = ... |
 | Consistency.cs:56:17:56:17 | k | Consistency.cs:57:9:57:13 | SSA def(k) | Consistency.cs:57:9:57:13 | ... = ... |
 | Consistency.cs:56:17:56:17 | k | Consistency.cs:58:9:58:13 | SSA def(k) | Consistency.cs:58:9:58:13 | ... = ... |
+| DefUse.cs:3:26:3:26 | w | DefUse.cs:3:26:3:26 | SSA param(w) | DefUse.cs:3:26:3:26 | w |
 | DefUse.cs:3:26:3:26 | w | DefUse.cs:19:13:19:18 | SSA def(w) | DefUse.cs:19:13:19:18 | ... = ... |
 | DefUse.cs:3:26:3:26 | w | DefUse.cs:29:13:29:18 | SSA def(w) | DefUse.cs:29:13:29:18 | ... = ... |
 | DefUse.cs:5:13:5:13 | x | DefUse.cs:5:13:5:17 | SSA def(x) | DefUse.cs:5:13:5:17 | Int32 x = ... |
@@ -50,17 +63,29 @@
 | DefUse.cs:97:13:97:14 | x5 | DefUse.cs:104:9:104:15 | SSA def(x5) | DefUse.cs:104:9:104:15 | ... += ... |
 | DefUse.cs:114:42:114:42 | i | DefUse.cs:114:47:114:52 | SSA def(i) | DefUse.cs:114:47:114:52 | ... = ... |
 | DefUse.cs:116:42:116:42 | i | DefUse.cs:116:47:116:51 | SSA def(i) | DefUse.cs:116:47:116:51 | ... = ... |
+| DefUse.cs:118:45:118:45 | i | DefUse.cs:118:45:118:45 | SSA param(i) | DefUse.cs:118:45:118:45 | i |
 | DefUse.cs:118:45:118:45 | i | DefUse.cs:118:68:118:72 | SSA def(i) | DefUse.cs:118:68:118:72 | ... = ... |
 | DefUse.cs:118:56:118:56 | j | DefUse.cs:118:61:118:65 | SSA def(j) | DefUse.cs:118:61:118:65 | ... = ... |
+| DefUse.cs:128:19:128:19 | i | DefUse.cs:128:19:128:19 | SSA param(i) | DefUse.cs:128:19:128:19 | i |
+| DefUse.cs:134:22:134:22 | d | DefUse.cs:134:22:134:22 | SSA param(d) | DefUse.cs:134:22:134:22 | d |
+| DefUse.cs:142:68:142:69 | ie | DefUse.cs:142:68:142:69 | SSA param(ie) | DefUse.cs:142:68:142:69 | ie |
 | DefUse.cs:144:22:144:22 | x | DefUse.cs:144:22:144:22 | SSA def(x) | DefUse.cs:144:22:144:22 | String x |
 | DefUse.cs:155:9:155:14 | this.Field4 | DefUse.cs:155:9:155:18 | SSA def(this.Field4) | DefUse.cs:155:9:155:18 | ... = ... |
 | DefUse.cs:171:23:171:23 | a | DefUse.cs:171:23:180:9 | SSA def(a) | DefUse.cs:171:23:180:9 | Action a = ... |
 | DefUse.cs:171:23:171:23 | a | DefUse.cs:186:9:190:9 | SSA def(a) | DefUse.cs:186:9:190:9 | ... = ... |
 | DefUse.cs:184:9:184:14 | this.Field5 | DefUse.cs:184:9:184:18 | SSA def(this.Field5) | DefUse.cs:184:9:184:18 | ... = ... |
 | DefUse.cs:188:13:188:18 | this.Field5 | DefUse.cs:188:13:188:22 | SSA def(this.Field5) | DefUse.cs:188:13:188:22 | ... = ... |
+| DefaultParam.cs:3:20:3:20 | b | DefaultParam.cs:3:20:3:20 | SSA param(b) | DefaultParam.cs:3:20:3:20 | b |
+| DefaultParam.cs:3:30:3:30 | s | DefaultParam.cs:3:30:3:30 | SSA param(s) | DefaultParam.cs:3:30:3:30 | s |
+| DefaultParam.cs:3:30:3:30 | s | DefaultParam.cs:3:34:3:35 | SSA param_default(s) | DefaultParam.cs:3:34:3:35 | s = ... |
+| DefaultParam.cs:3:42:3:42 | i | DefaultParam.cs:3:42:3:42 | SSA param(i) | DefaultParam.cs:3:42:3:42 | i |
+| DefaultParam.cs:3:42:3:42 | i | DefaultParam.cs:3:46:3:46 | SSA param_default(i) | DefaultParam.cs:3:46:3:46 | i = ... |
+| Example.cs:6:23:6:23 | i | Example.cs:6:23:6:23 | SSA param(i) | Example.cs:6:23:6:23 | i |
 | Example.cs:8:9:8:18 | this.Field | Example.cs:8:9:8:22 | SSA def(this.Field) | Example.cs:8:9:8:22 | ... = ... |
 | Example.cs:8:9:8:18 | this.Field | Example.cs:11:13:11:30 | SSA def(this.Field) | Example.cs:11:13:11:30 | ... = ... |
+| Example.cs:18:16:18:16 | p | Example.cs:18:16:18:16 | SSA param(p) | Example.cs:18:16:18:16 | p |
 | Example.cs:18:16:18:16 | p | Example.cs:23:13:23:17 | SSA def(p) | Example.cs:23:13:23:17 | ... = ... |
+| Example.cs:18:24:18:24 | b | Example.cs:18:24:18:24 | SSA param(b) | Example.cs:18:24:18:24 | b |
 | Fields.cs:18:15:18:15 | x | Fields.cs:20:9:20:14 | SSA def(x) | Fields.cs:20:9:20:14 | ... = ... |
 | Fields.cs:18:19:18:20 | this.xs | Fields.cs:24:9:24:23 | SSA def(this.xs) | Fields.cs:24:9:24:23 | ... = ... |
 | Fields.cs:30:13:30:13 | f | Fields.cs:30:13:30:28 | SSA def(f) | Fields.cs:30:13:30:28 | Fields f = ... |
@@ -76,8 +101,10 @@
 | Fields.cs:80:9:80:12 | f.xs | Fields.cs:88:9:88:25 | SSA def(f.xs) | Fields.cs:88:9:88:25 | ... = ... |
 | Fields.cs:82:9:82:15 | this.xs | Fields.cs:85:9:85:22 | SSA def(this.xs) | Fields.cs:85:9:85:22 | ... = ... |
 | Fields.cs:82:9:82:15 | this.xs | Fields.cs:87:9:87:22 | SSA def(this.xs) | Fields.cs:87:9:87:22 | ... = ... |
+| Fields.cs:95:19:95:19 | f | Fields.cs:95:19:95:19 | SSA param(f) | Fields.cs:95:19:95:19 | f |
 | Fields.cs:97:9:97:15 | f.Field | Fields.cs:97:9:97:30 | SSA def(f.Field) | Fields.cs:97:9:97:30 | ... = ... |
 | Fields.cs:102:9:102:18 | this.Field | Fields.cs:102:9:102:28 | SSA def(this.Field) | Fields.cs:102:9:102:28 | ... = ... |
+| Fields.cs:107:33:107:33 | f | Fields.cs:107:33:107:33 | SSA param(f) | Fields.cs:107:33:107:33 | f |
 | OutRef.cs:9:13:9:13 | j | OutRef.cs:9:13:9:17 | SSA def(j) | OutRef.cs:9:13:9:17 | Int32 j = ... |
 | OutRef.cs:9:13:9:13 | j | OutRef.cs:10:32:10:32 | SSA def(j) | OutRef.cs:10:32:10:32 | access to local variable j |
 | OutRef.cs:9:13:9:13 | j | OutRef.cs:22:22:22:22 | SSA def(j) | OutRef.cs:22:22:22:22 | access to local variable j |
@@ -91,8 +118,12 @@
 | OutRef.cs:18:13:18:13 | t | OutRef.cs:18:13:18:28 | SSA def(t) | OutRef.cs:18:13:18:28 | OutRef t = ... |
 | OutRef.cs:19:32:19:38 | t.Field | OutRef.cs:19:32:19:38 | SSA def(t.Field) | OutRef.cs:19:32:19:38 | access to field Field |
 | OutRef.cs:28:26:28:26 | i | OutRef.cs:30:9:30:13 | SSA def(i) | OutRef.cs:30:9:30:13 | ... = ... |
+| OutRef.cs:28:37:28:37 | j | OutRef.cs:28:37:28:37 | SSA param(j) | OutRef.cs:28:37:28:37 | j |
 | OutRef.cs:28:37:28:37 | j | OutRef.cs:31:9:31:13 | SSA def(j) | OutRef.cs:31:9:31:13 | ... = ... |
 | OutRef.cs:34:27:34:27 | i | OutRef.cs:36:9:36:13 | SSA def(i) | OutRef.cs:36:9:36:13 | ... = ... |
+| OutRef.cs:34:38:34:38 | j | OutRef.cs:34:38:34:38 | SSA param(j) | OutRef.cs:34:38:34:38 | j |
+| OutRef.cs:39:24:39:24 | b | OutRef.cs:39:24:39:24 | SSA param(b) | OutRef.cs:39:24:39:24 | b |
+| OutRef.cs:39:35:39:35 | j | OutRef.cs:39:35:39:35 | SSA param(j) | OutRef.cs:39:35:39:35 | j |
 | OutRef.cs:39:35:39:35 | j | OutRef.cs:42:13:42:17 | SSA def(j) | OutRef.cs:42:13:42:17 | ... = ... |
 | Patterns.cs:7:16:7:16 | o | Patterns.cs:7:16:7:23 | SSA def(o) | Patterns.cs:7:16:7:23 | Object o = ... |
 | Patterns.cs:8:22:8:23 | i1 | Patterns.cs:8:18:8:23 | SSA def(i1) | Patterns.cs:8:18:8:23 | Int32 i1 |
@@ -107,6 +138,7 @@
 | Properties.cs:31:19:31:22 | f.xs | Properties.cs:45:9:45:25 | SSA def(f.xs) | Properties.cs:45:9:45:25 | ... = ... |
 | Properties.cs:32:15:32:15 | z | Properties.cs:47:9:47:14 | SSA def(z) | Properties.cs:47:9:47:14 | ... = ... |
 | Properties.cs:32:19:32:20 | this.xs | Properties.cs:42:9:42:23 | SSA def(this.xs) | Properties.cs:42:9:42:23 | ... = ... |
+| Properties.cs:61:23:61:23 | i | Properties.cs:61:23:61:23 | SSA param(i) | Properties.cs:61:23:61:23 | i |
 | Properties.cs:61:23:61:23 | i | Properties.cs:63:16:63:18 | SSA def(i) | Properties.cs:63:16:63:18 | ...-- |
 | Properties.cs:73:13:73:13 | f | Properties.cs:73:13:73:32 | SSA def(f) | Properties.cs:73:13:73:32 | Properties f = ... |
 | Properties.cs:74:23:74:23 | a | Properties.cs:74:23:74:54 | SSA def(a) | Properties.cs:74:23:74:54 | Action a = ... |
@@ -116,8 +148,11 @@
 | Properties.cs:76:9:76:12 | f.xs | Properties.cs:84:9:84:25 | SSA def(f.xs) | Properties.cs:84:9:84:25 | ... = ... |
 | Properties.cs:78:9:78:15 | this.xs | Properties.cs:81:9:81:22 | SSA def(this.xs) | Properties.cs:81:9:81:22 | ... = ... |
 | Properties.cs:78:9:78:15 | this.xs | Properties.cs:83:9:83:22 | SSA def(this.xs) | Properties.cs:83:9:83:22 | ... = ... |
+| Properties.cs:106:37:106:37 | p | Properties.cs:106:37:106:37 | SSA param(p) | Properties.cs:106:37:106:37 | p |
+| Test.cs:5:15:5:20 | param1 | Test.cs:5:15:5:20 | SSA param(param1) | Test.cs:5:15:5:20 | param1 |
 | Test.cs:5:15:5:20 | param1 | Test.cs:27:17:27:24 | SSA def(param1) | Test.cs:27:17:27:24 | ...++ |
 | Test.cs:5:15:5:20 | param1 | Test.cs:41:13:41:23 | SSA def(param1) | Test.cs:41:13:41:23 | ... += ... |
+| Test.cs:5:67:5:72 | param2 | Test.cs:5:67:5:72 | SSA param(param2) | Test.cs:5:67:5:72 | param2 |
 | Test.cs:7:9:7:13 | this.field | Test.cs:7:9:7:17 | SSA def(this.field) | Test.cs:7:9:7:17 | ... = ... |
 | Test.cs:7:9:7:13 | this.field | Test.cs:21:13:21:22 | SSA def(this.field) | Test.cs:21:13:21:22 | ... = ... |
 | Test.cs:8:13:8:13 | x | Test.cs:8:13:8:17 | SSA def(x) | Test.cs:8:13:8:17 | Int32 x = ... |
@@ -133,10 +168,18 @@
 | Test.cs:34:18:34:18 | i | Test.cs:34:18:34:22 | SSA def(i) | Test.cs:34:18:34:22 | Int32 i = ... |
 | Test.cs:34:18:34:18 | i | Test.cs:34:33:34:35 | SSA def(i) | Test.cs:34:33:34:35 | ...++ |
 | Test.cs:39:22:39:22 | w | Test.cs:39:22:39:22 | SSA def(w) | Test.cs:39:22:39:22 | Int32 w |
+| Test.cs:46:16:46:18 | in | Test.cs:46:16:46:18 | SSA param(in) | Test.cs:46:16:46:18 | in |
 | Test.cs:46:29:46:32 | out | Test.cs:50:13:50:20 | SSA def(out) | Test.cs:50:13:50:20 | ... = ... |
 | Test.cs:46:29:46:32 | out | Test.cs:54:13:54:20 | SSA def(out) | Test.cs:54:13:54:20 | ... = ... |
 | Test.cs:56:13:56:17 | this.field | Test.cs:57:9:57:17 | SSA def(this.field) | Test.cs:57:9:57:17 | ... = ... |
+| Test.cs:62:16:62:16 | x | Test.cs:62:16:62:16 | SSA param(x) | Test.cs:62:16:62:16 | x |
 | Test.cs:68:45:68:45 | e | Test.cs:68:45:68:45 | SSA def(e) | Test.cs:68:45:68:45 | DivideByZeroException e |
+| Test.cs:76:24:76:25 | b1 | Test.cs:76:24:76:25 | SSA param(b1) | Test.cs:76:24:76:25 | b1 |
+| Test.cs:76:33:76:34 | b2 | Test.cs:76:33:76:34 | SSA param(b2) | Test.cs:76:33:76:34 | b2 |
+| Test.cs:76:42:76:43 | b3 | Test.cs:76:42:76:43 | SSA param(b3) | Test.cs:76:42:76:43 | b3 |
+| Test.cs:76:51:76:52 | b4 | Test.cs:76:51:76:52 | SSA param(b4) | Test.cs:76:51:76:52 | b4 |
+| Test.cs:76:60:76:61 | b5 | Test.cs:76:60:76:61 | SSA param(b5) | Test.cs:76:60:76:61 | b5 |
+| Test.cs:76:69:76:70 | b6 | Test.cs:76:69:76:70 | SSA param(b6) | Test.cs:76:69:76:70 | b6 |
 | Test.cs:78:13:78:13 | x | Test.cs:78:13:78:17 | SSA def(x) | Test.cs:78:13:78:17 | Int32 x = ... |
 | Test.cs:78:13:78:13 | x | Test.cs:108:13:108:17 | SSA def(x) | Test.cs:108:13:108:17 | ... = ... |
 | Tuples.cs:10:14:10:14 | x | Tuples.cs:10:9:10:54 | SSA def(x) | Tuples.cs:10:9:10:54 | ... = ... |
diff --git a/csharp/ql/test/library-tests/dataflow/ssa/SsaImplicitParameterDef.ql b/csharp/ql/test/library-tests/dataflow/ssa/SsaImplicitParameterDef.ql
index 8608b90746e..253fdea1ffa 100644
--- a/csharp/ql/test/library-tests/dataflow/ssa/SsaImplicitParameterDef.ql
+++ b/csharp/ql/test/library-tests/dataflow/ssa/SsaImplicitParameterDef.ql
@@ -1,5 +1,5 @@
 import csharp
 
-from Ssa::SourceVariable v, Ssa::ImplicitParameterDefinition def
+from Ssa::SourceVariable v, Ssa::ParameterDefinition def
 where v = def.getSourceVariable()
 select v, def, def.getParameter()
diff --git a/csharp/ql/test/library-tests/dataflow/ssa/SsaRead.expected b/csharp/ql/test/library-tests/dataflow/ssa/SsaRead.expected
index 96ae63b34fb..88ed6233672 100644
--- a/csharp/ql/test/library-tests/dataflow/ssa/SsaRead.expected
+++ b/csharp/ql/test/library-tests/dataflow/ssa/SsaRead.expected
@@ -100,8 +100,8 @@
 | DefUse.cs:184:9:184:14 | this.Field5 | DefUse.cs:191:9:191:11 | SSA call def(this.Field5) | DefUse.cs:192:13:192:18 | access to field Field5 |
 | DefUse.cs:188:13:188:18 | this.Field5 | DefUse.cs:188:13:188:22 | SSA def(this.Field5) | DefUse.cs:189:17:189:22 | access to field Field5 |
 | DefaultParam.cs:3:20:3:20 | b | DefaultParam.cs:3:20:3:20 | SSA param(b) | DefaultParam.cs:5:16:5:16 | access to parameter b |
-| DefaultParam.cs:3:30:3:30 | s | DefaultParam.cs:3:30:3:30 | SSA param(s) | DefaultParam.cs:5:20:5:20 | access to parameter s |
-| DefaultParam.cs:3:42:3:42 | i | DefaultParam.cs:3:42:3:42 | SSA param(i) | DefaultParam.cs:5:24:5:24 | access to parameter i |
+| DefaultParam.cs:3:30:3:30 | s | DefaultParam.cs:3:42:3:42 | SSA phi(s) | DefaultParam.cs:5:20:5:20 | access to parameter s |
+| DefaultParam.cs:3:42:3:42 | i | DefaultParam.cs:4:5:6:5 | SSA phi(i) | DefaultParam.cs:5:24:5:24 | access to parameter i |
 | Example.cs:6:23:6:23 | i | Example.cs:6:23:6:23 | SSA param(i) | Example.cs:8:22:8:22 | access to parameter i |
 | Example.cs:6:23:6:23 | i | Example.cs:6:23:6:23 | SSA param(i) | Example.cs:10:13:10:13 | access to parameter i |
 | Example.cs:6:23:6:23 | i | Example.cs:6:23:6:23 | SSA param(i) | Example.cs:11:26:11:26 | access to parameter i |
diff --git a/csharp/ql/test/library-tests/dataflow/ssa/SsaUltimateDef.expected b/csharp/ql/test/library-tests/dataflow/ssa/SsaUltimateDef.expected
index c3ccef11a44..00bacccf157 100644
--- a/csharp/ql/test/library-tests/dataflow/ssa/SsaUltimateDef.expected
+++ b/csharp/ql/test/library-tests/dataflow/ssa/SsaUltimateDef.expected
@@ -101,7 +101,13 @@
 | DefUse.cs:188:13:188:18 | this.Field5 | DefUse.cs:188:13:188:22 | SSA def(this.Field5) | DefUse.cs:188:13:188:22 | SSA def(this.Field5) |
 | DefaultParam.cs:3:20:3:20 | b | DefaultParam.cs:3:20:3:20 | SSA param(b) | DefaultParam.cs:3:20:3:20 | SSA param(b) |
 | DefaultParam.cs:3:30:3:30 | s | DefaultParam.cs:3:30:3:30 | SSA param(s) | DefaultParam.cs:3:30:3:30 | SSA param(s) |
+| DefaultParam.cs:3:30:3:30 | s | DefaultParam.cs:3:34:3:35 | SSA param_default(s) | DefaultParam.cs:3:34:3:35 | SSA param_default(s) |
+| DefaultParam.cs:3:30:3:30 | s | DefaultParam.cs:3:42:3:42 | SSA phi(s) | DefaultParam.cs:3:30:3:30 | SSA param(s) |
+| DefaultParam.cs:3:30:3:30 | s | DefaultParam.cs:3:42:3:42 | SSA phi(s) | DefaultParam.cs:3:34:3:35 | SSA param_default(s) |
 | DefaultParam.cs:3:42:3:42 | i | DefaultParam.cs:3:42:3:42 | SSA param(i) | DefaultParam.cs:3:42:3:42 | SSA param(i) |
+| DefaultParam.cs:3:42:3:42 | i | DefaultParam.cs:3:46:3:46 | SSA param_default(i) | DefaultParam.cs:3:46:3:46 | SSA param_default(i) |
+| DefaultParam.cs:3:42:3:42 | i | DefaultParam.cs:4:5:6:5 | SSA phi(i) | DefaultParam.cs:3:42:3:42 | SSA param(i) |
+| DefaultParam.cs:3:42:3:42 | i | DefaultParam.cs:4:5:6:5 | SSA phi(i) | DefaultParam.cs:3:46:3:46 | SSA param_default(i) |
 | Example.cs:6:23:6:23 | i | Example.cs:6:23:6:23 | SSA param(i) | Example.cs:6:23:6:23 | SSA param(i) |
 | Example.cs:8:9:8:18 | this.Field | Example.cs:8:9:8:22 | SSA def(this.Field) | Example.cs:8:9:8:22 | SSA def(this.Field) |
 | Example.cs:8:9:8:18 | this.Field | Example.cs:10:9:13:24 | SSA phi(this.Field) | Example.cs:8:9:8:22 | SSA def(this.Field) |