diff --git a/src/System.Diagnostics.Metrics.Temp/Counter.cs b/src/System.Diagnostics.Metrics.Temp/Counter.cs
index 9e611cc6348..7e02531fd74 100644
--- a/src/System.Diagnostics.Metrics.Temp/Counter.cs
+++ b/src/System.Diagnostics.Metrics.Temp/Counter.cs
@@ -26,10 +26,10 @@ namespace System.Diagnostics.Metrics
     /// </summary>
     /// <typeparam name="T">TBD.</typeparam>
     public sealed class Counter<T> : Instrument<T>
-        where T : unmanaged
+        where T : struct
     {
-        internal Counter(Meter meter, string name, string? description, string? unit)
-            : base(meter, name, description, unit)
+        internal Counter(Meter meter, string name, string? unit, string? description)
+            : base(meter, name, unit, description)
         {
             this.Publish();
         }
@@ -37,62 +37,62 @@ internal Counter(Meter meter, string name, string? description, string? unit)
         /// <summary>
         /// TBD.
         /// </summary>
-        public void Add(T measurement)
+        public void Add(T delta)
         {
-            this.RecordMeasurement(measurement);
+            this.RecordMeasurement(delta);
         }
 
         /// <summary>
         /// TBD.
         /// </summary>
         public void Add(
-            T measurement,
+            T delta,
             KeyValuePair<string, object?> tag1)
         {
-            this.RecordMeasurement(measurement, tag1);
+            this.RecordMeasurement(delta, tag1);
         }
 
         /// <summary>
         /// TBD.
         /// </summary>
         public void Add(
-            T measurement,
+            T delta,
             KeyValuePair<string, object?> tag1,
             KeyValuePair<string, object?> tag2)
         {
-            this.RecordMeasurement(measurement, tag1, tag2);
+            this.RecordMeasurement(delta, tag1, tag2);
         }
 
         /// <summary>
         /// TBD.
         /// </summary>
         public void Add(
-            T measurement,
+            T delta,
             KeyValuePair<string, object?> tag1,
             KeyValuePair<string, object?> tag2,
             KeyValuePair<string, object?> tag3)
         {
-            this.RecordMeasurement(measurement, tag1, tag2, tag3);
+            this.RecordMeasurement(delta, tag1, tag2, tag3);
         }
 
         /// <summary>
         /// TBD.
         /// </summary>
         public void Add(
-            T measurement,
+            T delta,
             ReadOnlySpan<KeyValuePair<string, object?>> tags)
         {
-            this.RecordMeasurement(measurement, tags);
+            this.RecordMeasurement(delta, tags);
         }
 
         /// <summary>
         /// TBD.
         /// </summary>
         public void Add(
-            T measurement,
+            T delta,
             params KeyValuePair<string, object?>[] tags)
         {
-            this.RecordMeasurement(measurement, tags);
+            this.RecordMeasurement(delta, tags);
         }
     }
 }
diff --git a/src/System.Diagnostics.Metrics.Temp/Histogram.cs b/src/System.Diagnostics.Metrics.Temp/Histogram.cs
index daac125a833..a68104edc09 100644
--- a/src/System.Diagnostics.Metrics.Temp/Histogram.cs
+++ b/src/System.Diagnostics.Metrics.Temp/Histogram.cs
@@ -27,10 +27,10 @@ namespace System.Diagnostics.Metrics
     /// </summary>
     /// <typeparam name="T">TBD.</typeparam>
     public sealed class Histogram<T> : Instrument<T>
-        where T : unmanaged
+        where T : struct
     {
-        internal Histogram(Meter meter, string name, string? description, string? unit)
-            : base(meter, name, description, unit)
+        internal Histogram(Meter meter, string name, string? unit, string? description)
+            : base(meter, name, unit, description)
         {
             this.Publish();
         }
@@ -38,62 +38,62 @@ internal Histogram(Meter meter, string name, string? description, string? unit)
         /// <summary>
         /// TBD.
         /// </summary>
-        public void Record(T measurement)
+        public void Record(T value)
         {
-            this.RecordMeasurement(measurement);
+            this.RecordMeasurement(value);
         }
 
         /// <summary>
         /// TBD.
         /// </summary>
         public void Record(
-            T measurement,
+            T value,
             KeyValuePair<string, object?> tag1)
         {
-            this.RecordMeasurement(measurement, tag1);
+            this.RecordMeasurement(value, tag1);
         }
 
         /// <summary>
         /// TBD.
         /// </summary>
         public void Record(
-            T measurement,
+            T value,
             KeyValuePair<string, object?> tag1,
             KeyValuePair<string, object?> tag2)
         {
-            this.RecordMeasurement(measurement, tag1, tag2);
+            this.RecordMeasurement(value, tag1, tag2);
         }
 
         /// <summary>
         /// TBD.
         /// </summary>
         public void Record(
-            T measurement,
+            T value,
             KeyValuePair<string, object?> tag1,
             KeyValuePair<string, object?> tag2,
             KeyValuePair<string, object?> tag3)
         {
-            this.RecordMeasurement(measurement, tag1, tag2, tag3);
+            this.RecordMeasurement(value, tag1, tag2, tag3);
         }
 
         /// <summary>
         /// TBD.
         /// </summary>
         public void Record(
-            T measurement,
+            T value,
             ReadOnlySpan<KeyValuePair<string, object?>> tags)
         {
-            this.RecordMeasurement(measurement, tags);
+            this.RecordMeasurement(value, tags);
         }
 
         /// <summary>
         /// TBD.
         /// </summary>
         public void Record(
-            T measurement,
+            T value,
             params KeyValuePair<string, object?>[] tags)
         {
-            this.RecordMeasurement(measurement, tags);
+            this.RecordMeasurement(value, tags);
         }
     }
 }
diff --git a/src/System.Diagnostics.Metrics.Temp/Instrument.cs b/src/System.Diagnostics.Metrics.Temp/Instrument.cs
index 1662bd02fba..5e3b5c531e9 100644
--- a/src/System.Diagnostics.Metrics.Temp/Instrument.cs
+++ b/src/System.Diagnostics.Metrics.Temp/Instrument.cs
@@ -34,12 +34,12 @@ public abstract class Instrument
         /// Initializes a new instance of the <see cref="Instrument"/> class.
         /// Protected constructor to initialize the common instrument properties.
         /// </summary>
-        protected Instrument(Meter meter, string name, string? description, string? unit)
+        protected Instrument(Meter meter, string name, string? unit, string? description)
         {
             this.Meter = meter;
             this.Name = name;
-            this.Description = description;
             this.Unit = unit;
+            this.Description = description;
         }
 
         /// <summary>
diff --git a/src/System.Diagnostics.Metrics.Temp/InstrumentT.cs b/src/System.Diagnostics.Metrics.Temp/InstrumentT.cs
index dd9f7b6a07a..6976a91e3dd 100644
--- a/src/System.Diagnostics.Metrics.Temp/InstrumentT.cs
+++ b/src/System.Diagnostics.Metrics.Temp/InstrumentT.cs
@@ -27,14 +27,14 @@ namespace System.Diagnostics.Metrics
     /// </summary>
     /// <typeparam name="T">TBD.</typeparam>
     public abstract class Instrument<T> : Instrument
-        where T : unmanaged
+        where T : struct
     {
         /// <summary>
         /// Initializes a new instance of the <see cref="Instrument{T}"/> class.
         /// Protected constructor to create the instrument with the common properties.
         /// </summary>
-        protected Instrument(Meter meter, string name, string? description, string? unit)
-            : base(meter, name, description, unit)
+        protected Instrument(Meter meter, string name, string? unit, string? description)
+            : base(meter, name, unit, description)
         {
         }
 
diff --git a/src/System.Diagnostics.Metrics.Temp/Measurement.cs b/src/System.Diagnostics.Metrics.Temp/Measurement.cs
index 1d04c6bd3b8..27a97efdcfe 100644
--- a/src/System.Diagnostics.Metrics.Temp/Measurement.cs
+++ b/src/System.Diagnostics.Metrics.Temp/Measurement.cs
@@ -27,7 +27,7 @@ namespace System.Diagnostics.Metrics
     /// </summary>
     /// <typeparam name="T">TBD.</typeparam>
     public struct Measurement<T>
-        where T : unmanaged
+        where T : struct
     {
         /// <summary>
         /// Initializes a new instance of the <see cref="Measurement{T}"/> struct.
diff --git a/src/System.Diagnostics.Metrics.Temp/Meter.cs b/src/System.Diagnostics.Metrics.Temp/Meter.cs
index 31229425446..a5c8b821fac 100644
--- a/src/System.Diagnostics.Metrics.Temp/Meter.cs
+++ b/src/System.Diagnostics.Metrics.Temp/Meter.cs
@@ -61,11 +61,11 @@ public Meter(string name, string? version)
         /// <typeparam name="T">TBD.</typeparam>
         public Counter<T> CreateCounter<T>(
             string name,
-            string? description = null,
-            string? unit = null)
-            where T : unmanaged
+            string? unit = null,
+            string? description = null)
+            where T : struct
         {
-            return new Counter<T>(this, name, description, unit);
+            return new Counter<T>(this, name, unit, description);
         }
 
         /// <summary>
@@ -74,11 +74,11 @@ public Counter<T> CreateCounter<T>(
         /// <typeparam name="T">TBD.</typeparam>
         public Histogram<T> CreateHistogram<T>(
             string name,
-            string? description = null,
-            string? unit = null)
-            where T : unmanaged
+            string? unit = null,
+            string? description = null)
+            where T : struct
         {
-            return new Histogram<T>(this, name, description, unit);
+            return new Histogram<T>(this, name, unit, description);
         }
 
         /// <summary>
@@ -88,9 +88,9 @@ public Histogram<T> CreateHistogram<T>(
         public ObservableCounter<T> CreateObservableCounter<T>(
             string name,
             Func<T> observeValue,
-            string? description = null,
-            string? unit = null)
-            where T : unmanaged
+            string? unit = null,
+            string? description = null)
+            where T : struct
         {
             return new ObservableCounter<T>(
                 this,
@@ -99,8 +99,8 @@ public ObservableCounter<T> CreateObservableCounter<T>(
                     {
                         new Measurement<T>(observeValue()),
                     },
-                description,
-                unit);
+                unit,
+                description);
         }
 
         /// <summary>
@@ -110,9 +110,9 @@ public ObservableCounter<T> CreateObservableCounter<T>(
         public ObservableCounter<T> CreateObservableCounter<T>(
             string name,
             Func<Measurement<T>> observeValue,
-            string? description = null,
-            string? unit = null)
-            where T : unmanaged
+            string? unit = null,
+            string? description = null)
+            where T : struct
         {
             return new ObservableCounter<T>(
                 this,
@@ -121,8 +121,8 @@ public ObservableCounter<T> CreateObservableCounter<T>(
                     {
                         observeValue(),
                     },
-                description,
-                unit);
+                unit,
+                description);
         }
 
         /// <summary>
@@ -132,11 +132,11 @@ public ObservableCounter<T> CreateObservableCounter<T>(
         public ObservableCounter<T> CreateObservableCounter<T>(
             string name,
             Func<IEnumerable<Measurement<T>>> observeValues,
-            string? description = null,
-            string? unit = null)
-            where T : unmanaged
+            string? unit = null,
+            string? description = null)
+            where T : struct
         {
-            return new ObservableCounter<T>(this, name, observeValues, description, unit);
+            return new ObservableCounter<T>(this, name, observeValues, unit, description);
         }
 
         /// <summary>
@@ -146,9 +146,9 @@ public ObservableCounter<T> CreateObservableCounter<T>(
         public ObservableGauge<T> CreateObservableGauge<T>(
             string name,
             Func<T> observeValue,
-            string? description = null,
-            string? unit = null)
-            where T : unmanaged
+            string? unit = null,
+            string? description = null)
+            where T : struct
         {
             return new ObservableGauge<T>(
                 this,
@@ -157,8 +157,8 @@ public ObservableGauge<T> CreateObservableGauge<T>(
                     {
                         new Measurement<T>(observeValue()),
                     },
-                description,
-                unit);
+                unit,
+                description);
         }
 
         /// <summary>
@@ -168,9 +168,9 @@ public ObservableGauge<T> CreateObservableGauge<T>(
         public ObservableGauge<T> CreateObservableGauge<T>(
             string name,
             Func<Measurement<T>> observeValue,
-            string? description = null,
-            string? unit = null)
-            where T : unmanaged
+            string? unit = null,
+            string? description = null)
+            where T : struct
         {
             return new ObservableGauge<T>(
                 this,
@@ -179,8 +179,8 @@ public ObservableGauge<T> CreateObservableGauge<T>(
                     {
                         observeValue(),
                     },
-                description,
-                unit);
+                unit,
+                description);
         }
 
         /// <summary>
@@ -190,11 +190,11 @@ public ObservableGauge<T> CreateObservableGauge<T>(
         public ObservableGauge<T> CreateObservableGauge<T>(
             string name,
             Func<IEnumerable<Measurement<T>>> observeValues,
-            string? description = null,
-            string? unit = null)
-            where T : unmanaged
+            string? unit = null,
+            string? description = null)
+            where T : struct
         {
-            return new ObservableGauge<T>(this, name, observeValues, description, unit);
+            return new ObservableGauge<T>(this, name, observeValues, unit, description);
         }
 
         /// <summary>
@@ -204,9 +204,9 @@ public ObservableGauge<T> CreateObservableGauge<T>(
         public ObservableUpDownCounter<T> CreateObservableUpDownCounter<T>(
             string name,
             Func<T> observeValue,
-            string? description = null,
-            string? unit = null)
-            where T : unmanaged
+            string? unit = null,
+            string? description = null)
+            where T : struct
         {
             return new ObservableUpDownCounter<T>(
                 this,
@@ -215,8 +215,8 @@ public ObservableUpDownCounter<T> CreateObservableUpDownCounter<T>(
                     {
                         new Measurement<T>(observeValue()),
                     },
-                description,
-                unit);
+                unit,
+                description);
         }
 
         /// <summary>
@@ -226,9 +226,9 @@ public ObservableUpDownCounter<T> CreateObservableUpDownCounter<T>(
         public ObservableUpDownCounter<T> CreateObservableUpDownCounter<T>(
             string name,
             Func<Measurement<T>> observeValue,
-            string? description = null,
-            string? unit = null)
-            where T : unmanaged
+            string? unit = null,
+            string? description = null)
+            where T : struct
         {
             return new ObservableUpDownCounter<T>(
                 this,
@@ -237,8 +237,8 @@ public ObservableUpDownCounter<T> CreateObservableUpDownCounter<T>(
                     {
                         observeValue(),
                     },
-                description,
-                unit);
+                unit,
+                description);
         }
 
         /// <summary>
@@ -248,11 +248,11 @@ public ObservableUpDownCounter<T> CreateObservableUpDownCounter<T>(
         public ObservableUpDownCounter<T> CreateObservableUpDownCounter<T>(
             string name,
             Func<IEnumerable<Measurement<T>>> observeValues,
-            string? description = null,
-            string? unit = null)
-            where T : unmanaged
+            string? unit = null,
+            string? description = null)
+            where T : struct
         {
-            return new ObservableUpDownCounter<T>(this, name, observeValues, description, unit);
+            return new ObservableUpDownCounter<T>(this, name, observeValues, unit, description);
         }
 
         /// <summary>
diff --git a/src/System.Diagnostics.Metrics.Temp/MeterListener.cs b/src/System.Diagnostics.Metrics.Temp/MeterListener.cs
index 5d4efc1c10a..b33a54c1c91 100644
--- a/src/System.Diagnostics.Metrics.Temp/MeterListener.cs
+++ b/src/System.Diagnostics.Metrics.Temp/MeterListener.cs
@@ -31,7 +31,8 @@ public delegate void MeasurementCallback<T>(
         Instrument instrument,
         T measurement,
         ReadOnlySpan<KeyValuePair<string, object?>> tags,
-        object? state);
+        object? state)
+        where T : struct;
 
     /// <summary>
     /// The listener class can be used to listen to observable and non-observable instrument
@@ -94,6 +95,7 @@ public void EnableMeasurementEvents(Instrument instrument, object? state = null)
         /// </summary>
         /// <typeparam name="T">TBD.</typeparam>
         public void SetMeasurementEventCallback<T>(MeasurementCallback<T>? measurementCallback)
+            where T : struct
         {
             this.Callbacks.TryAdd(typeof(T), (object?)measurementCallback);
         }
@@ -105,13 +107,6 @@ public void Start()
         {
         }
 
-        /// <summary>
-        /// TBD.
-        /// </summary>
-        public void Stop()
-        {
-        }
-
         /// <summary>
         /// Call all Observable instruments to get the recorded measurements reported to the
         /// callbacks enabled by SetMeasurementEventCallback_T.
diff --git a/src/System.Diagnostics.Metrics.Temp/ObservableCounter.cs b/src/System.Diagnostics.Metrics.Temp/ObservableCounter.cs
index 29af86729c2..19c4bf806f0 100644
--- a/src/System.Diagnostics.Metrics.Temp/ObservableCounter.cs
+++ b/src/System.Diagnostics.Metrics.Temp/ObservableCounter.cs
@@ -27,12 +27,12 @@ namespace System.Diagnostics.Metrics
     /// </summary>
     /// <typeparam name="T">TBD.</typeparam>
     public sealed class ObservableCounter<T> : ObservableInstrument<T>
-        where T : unmanaged
+        where T : struct
     {
         private Func<IEnumerable<Measurement<T>>> observeValues;
 
-        internal ObservableCounter(Meter meter, string name, Func<IEnumerable<Measurement<T>>> observeValues, string? description, string? unit)
-            : base(meter, name, description, unit)
+        internal ObservableCounter(Meter meter, string name, Func<IEnumerable<Measurement<T>>> observeValues, string? unit, string? description)
+            : base(meter, name, unit, description)
         {
             this.observeValues = observeValues;
             this.Publish();
diff --git a/src/System.Diagnostics.Metrics.Temp/ObservableGauge.cs b/src/System.Diagnostics.Metrics.Temp/ObservableGauge.cs
index 6418655622e..94eca5c393e 100644
--- a/src/System.Diagnostics.Metrics.Temp/ObservableGauge.cs
+++ b/src/System.Diagnostics.Metrics.Temp/ObservableGauge.cs
@@ -27,12 +27,12 @@ namespace System.Diagnostics.Metrics
     /// </summary>
     /// <typeparam name="T">TBD.</typeparam>
     public sealed class ObservableGauge<T> : ObservableInstrument<T>
-        where T : unmanaged
+        where T : struct
     {
         private Func<IEnumerable<Measurement<T>>> observeValues;
 
-        internal ObservableGauge(Meter meter, string name, Func<IEnumerable<Measurement<T>>> observeValues, string? description, string? unit)
-            : base(meter, name, description, unit)
+        internal ObservableGauge(Meter meter, string name, Func<IEnumerable<Measurement<T>>> observeValues, string? unit, string? description)
+            : base(meter, name, unit, description)
         {
             this.observeValues = observeValues;
             this.Publish();
diff --git a/src/System.Diagnostics.Metrics.Temp/ObservableInstrument.cs b/src/System.Diagnostics.Metrics.Temp/ObservableInstrument.cs
index c8070f6da22..5ff3908afcb 100644
--- a/src/System.Diagnostics.Metrics.Temp/ObservableInstrument.cs
+++ b/src/System.Diagnostics.Metrics.Temp/ObservableInstrument.cs
@@ -26,7 +26,7 @@ namespace System.Diagnostics.Metrics
     /// </summary>
     /// <typeparam name="T">TBD.</typeparam>
     public abstract class ObservableInstrument<T> : Instrument
-        where T : unmanaged
+        where T : struct
     {
         /// <summary>
         /// Initializes a new instance of the <see cref="ObservableInstrument{T}"/> class.
@@ -35,8 +35,8 @@ public abstract class ObservableInstrument<T> : Instrument
         protected ObservableInstrument(
             Meter meter,
             string name,
-            string? description,
-            string? unit)
+            string? unit,
+            string? description)
             : base(meter, name, description, unit)
         {
         }
diff --git a/src/System.Diagnostics.Metrics.Temp/ObservableUpDownCounter.cs b/src/System.Diagnostics.Metrics.Temp/ObservableUpDownCounter.cs
index d0ac83931fa..bf74eef8f8e 100644
--- a/src/System.Diagnostics.Metrics.Temp/ObservableUpDownCounter.cs
+++ b/src/System.Diagnostics.Metrics.Temp/ObservableUpDownCounter.cs
@@ -27,12 +27,12 @@ namespace System.Diagnostics.Metrics
     /// </summary>
     /// <typeparam name="T">TBD.</typeparam>
     public sealed class ObservableUpDownCounter<T> : ObservableInstrument<T>
-        where T : unmanaged
+        where T : struct
     {
         private Func<IEnumerable<Measurement<T>>> observeValues;
 
         internal ObservableUpDownCounter(Meter meter, string name, Func<IEnumerable<Measurement<T>>> observeValues, string? description, string? unit)
-            : base(meter, name, description, unit)
+            : base(meter, name, unit, description)
         {
             this.observeValues = observeValues;
             this.Publish();