diff --git a/src/main/scala/diplomacy/Nodes.scala b/src/main/scala/diplomacy/Nodes.scala
index 8906f64b..06103b3c 100644
--- a/src/main/scala/diplomacy/Nodes.scala
+++ b/src/main/scala/diplomacy/Nodes.scala
@@ -4,10 +4,27 @@ package freechips.rocketchip.diplomacy
 
 import Chisel._
 import chisel3.internal.sourceinfo.SourceInfo
-import freechips.rocketchip.config.Parameters
+import freechips.rocketchip.config.{Parameters,Field}
 import freechips.rocketchip.util.HeterogeneousBag
 import scala.collection.mutable.ListBuffer
 
+object CardinalityInferenceDirection {
+  val cases = Seq(SOURCE_TO_SINK, SINK_TO_SOURCE, NO_INFERENCE)
+  sealed trait T {
+    def flip = this match {
+      case SOURCE_TO_SINK => SINK_TO_SOURCE
+      case SINK_TO_SOURCE => SOURCE_TO_SINK
+      case NO_INFERENCE   => NO_INFERENCE
+    }
+  }
+
+  case object SOURCE_TO_SINK extends T
+  case object SINK_TO_SOURCE extends T
+  case object NO_INFERENCE   extends T
+}
+
+case object CardinalityInferenceDirectionKey extends Field[CardinalityInferenceDirection.T]
+
 // DI = Downwards flowing Parameters received on the inner side of the node
 // UI = Upwards   flowing Parameters generated by the inner side of the node
 // EI = Edge Parameters describing a connection on the inner side of the node
@@ -84,6 +101,8 @@ trait InwardNodeHandle[DI, UI, BI <: Data]
     inward.:*=(h)(p, sourceInfo)
   def :=* (h: OutwardNodeHandle[DI, UI, BI])(implicit p: Parameters, sourceInfo: SourceInfo): Option[MonitorBase] =
     inward.:=*(h)(p, sourceInfo)
+  def :=? (h: OutwardNodeHandle[DI, UI, BI])(implicit p: Parameters, sourceInfo: SourceInfo): Option[MonitorBase] =
+    inward.:=?(h)(p, sourceInfo)
 }
 
 sealed trait NodeBinding
@@ -264,6 +283,14 @@ abstract class MixedNode[DI, UI, EI, BI <: Data, DO, UO, EO, BO <: Data](
   override def :=  (h: OutwardNodeHandle[DI, UI, BI])(implicit p: Parameters, sourceInfo: SourceInfo): Option[MonitorBase] = bind(h, BIND_ONCE, true)
   override def :*= (h: OutwardNodeHandle[DI, UI, BI])(implicit p: Parameters, sourceInfo: SourceInfo): Option[MonitorBase] = bind(h, BIND_STAR, true)
   override def :=* (h: OutwardNodeHandle[DI, UI, BI])(implicit p: Parameters, sourceInfo: SourceInfo): Option[MonitorBase] = bind(h, BIND_QUERY, true)
+  override def :=? (h: OutwardNodeHandle[DI, UI, BI])(implicit p: Parameters, sourceInfo: SourceInfo): Option[MonitorBase] = {
+    p.lift(CardinalityInferenceDirectionKey) match {
+      case Some(CardinalityInferenceDirection.SOURCE_TO_SINK) => this :=* h
+      case Some(CardinalityInferenceDirection.SINK_TO_SOURCE) => this :*= h
+      case Some(CardinalityInferenceDirection.NO_INFERENCE)   => this :=  h
+      case None                                               => this :=  h
+    }
+  }
 
   def connectButDontMonitor(h: OutwardNodeHandle[DI, UI, BI])(implicit p: Parameters, sourceInfo: SourceInfo): Option[MonitorBase] = bind(h, BIND_ONCE, false)
   def connectButDontMonitorSlaves(h: OutwardNodeHandle[DI, UI, BI])(implicit p: Parameters, sourceInfo: SourceInfo): Option[MonitorBase] = bind(h, BIND_STAR, false)
diff --git a/src/main/scala/diplomacy/package.scala b/src/main/scala/diplomacy/package.scala
index 64219a1c..0567f2fa 100644
--- a/src/main/scala/diplomacy/package.scala
+++ b/src/main/scala/diplomacy/package.scala
@@ -3,6 +3,7 @@
 package freechips.rocketchip
 
 import chisel3.internal.sourceinfo.{SourceInfo, SourceLine, UnlocatableSourceInfo}
+import freechips.rocketchip.config.Parameters
 
 package object diplomacy
 {
@@ -20,4 +21,20 @@ package object diplomacy
       bitIndexes(x.clearBit(lowest), lowest +: tail)
     }
   }
+
+  def LeftStar[T](body: Parameters => T)(implicit p: Parameters) = body(p.alterPartial {
+    case CardinalityInferenceDirectionKey => CardinalityInferenceDirection.SINK_TO_SOURCE
+  })
+  def RightStar[T](body: Parameters => T)(implicit p: Parameters) = body(p.alterPartial {
+    case CardinalityInferenceDirectionKey => CardinalityInferenceDirection.SOURCE_TO_SINK
+  })
+  def NoStar[T](body: Parameters => T)(implicit p: Parameters) = body(p.alterPartial {
+    case CardinalityInferenceDirectionKey => CardinalityInferenceDirection.NO_INFERENCE
+  })
+  def FlipStar[T](body: Parameters => T)(implicit p: Parameters) = body(p.alterPartial {
+    case CardinalityInferenceDirectionKey => p
+      .lift(CardinalityInferenceDirectionKey)
+      .map(_.flip)
+      .getOrElse(CardinalityInferenceDirection.NO_INFERENCE)
+  })
 }