diff --git a/src/nt/ntmultiChannel.cpp b/src/nt/ntmultiChannel.cpp
index fa21d93..2f4cb30 100644
--- a/src/nt/ntmultiChannel.cpp
+++ b/src/nt/ntmultiChannel.cpp
@@ -318,12 +318,34 @@ bool NTMultiChannel::isCompatible(PVStructurePtr const &pvStructure)
     return isCompatible(pvStructure->getStructure());
 }
 
+
+bool NTMultiChannel::isValid()
+{
+    size_t valueLength = getValue()->getLength();
+    if (getChannelName()->getLength() != valueLength) return false;
+
+    PVScalarArrayPtr arrayFields[] = {
+          getSeverity(), getStatus(), getMessage(), 
+          getSecondsPastEpoch(), getNanoseconds(), getUserTag()
+    };
+    size_t N = sizeof(arrayFields)/sizeof(arrayFields[0]);
+
+    PVScalarArrayPtr arrayField;
+    for (PVScalarArrayPtr * pa = arrayFields; pa != arrayFields+N; ++pa)
+    {
+        arrayField = *pa;
+        if (arrayField.get() && arrayField->getLength() != valueLength)
+            return false;
+    }
+    return true; 
+}
+
+
 NTMultiChannelBuilderPtr NTMultiChannel::createBuilder()
 {
     return NTMultiChannelBuilderPtr(new detail::NTMultiChannelBuilder());
 }
 
-
 NTMultiChannel::NTMultiChannel(PVStructurePtr const & pvStructure)
 : pvNTMultiChannel(pvStructure),
   pvTimeStamp(pvStructure->getSubField<PVStructure>("timeStamp")),
diff --git a/src/nt/ntscalarMultiChannel.cpp b/src/nt/ntscalarMultiChannel.cpp
index 4ea42cb..72efecb 100644
--- a/src/nt/ntscalarMultiChannel.cpp
+++ b/src/nt/ntscalarMultiChannel.cpp
@@ -315,6 +315,27 @@ bool NTScalarMultiChannel::isCompatible(PVStructurePtr const &pvStructure)
     return isCompatible(pvStructure->getStructure());
 }
 
+bool NTScalarMultiChannel::isValid()
+{
+    size_t valueLength = getValue()->getLength();
+    if (getChannelName()->getLength() != valueLength) return false;
+
+    PVScalarArrayPtr arrayFields[] = {
+          getSeverity(), getStatus(), getMessage(), 
+          getSecondsPastEpoch(), getNanoseconds(), getUserTag()
+    };
+    size_t N = sizeof(arrayFields)/sizeof(arrayFields[0]);
+
+    PVScalarArrayPtr arrayField;
+    for (PVScalarArrayPtr * pa = arrayFields; pa != arrayFields+N; ++pa)
+    {
+        arrayField = *pa;
+        if (arrayField.get() && arrayField->getLength() != valueLength)
+            return false;
+    }
+    return true; 
+}
+
 NTScalarMultiChannelBuilderPtr NTScalarMultiChannel::createBuilder()
 {
     return NTScalarMultiChannelBuilderPtr(new detail::NTScalarMultiChannelBuilder());
diff --git a/src/nt/nttable.cpp b/src/nt/nttable.cpp
index 1964aca..d584a42 100644
--- a/src/nt/nttable.cpp
+++ b/src/nt/nttable.cpp
@@ -190,6 +190,32 @@ bool NTTable::isCompatible(PVStructurePtr const & pvStructure)
     return isCompatible(pvStructure->getStructure());
 }
 
+bool NTTable::isValid()
+{
+    PVFieldPtrArray const & columns = pvValue->getPVFields();
+        
+    if (getLabels()->getLength() != columns.size()) return false;
+    boolean first = true;
+    int length = 0;
+    for (PVFieldPtrArray::const_iterator it = columns.begin();
+        it != columns.end();++it)
+    {
+        PVScalarArrayPtr column = std::tr1::dynamic_pointer_cast<PVScalarArray>(*it);
+        if (!column.get()) return false;
+        int colLength = column->getLength();
+        if (first)
+        {
+            length = colLength;
+            first = false;
+        }
+        else if (length != colLength)
+            return false;
+    }
+
+    return true;
+}
+
+
 NTTableBuilderPtr NTTable::createBuilder()
 {
     return NTTableBuilderPtr(new detail::NTTableBuilder());
diff --git a/src/nt/nturi.cpp b/src/nt/nturi.cpp
index 378d72d..1d0d824 100644
--- a/src/nt/nturi.cpp
+++ b/src/nt/nturi.cpp
@@ -194,6 +194,11 @@ bool NTURI::isCompatible(PVStructurePtr const & pvStructure)
     return isCompatible(pvStructure->getStructure());
 }
 
+bool NTURI::isValid()
+{
+    return true;
+}
+
 NTURIBuilderPtr NTURI::createBuilder()
 {
     return NTURIBuilderPtr(new detail::NTURIBuilder());