From ea7d7ec9ed1a92ffff15b19743f2730d78f22314 Mon Sep 17 00:00:00 2001
From: David Ashpole <dashpole@google.com>
Date: Tue, 16 Dec 2025 19:54:53 +0000
Subject: [PATCH 01/12] add DefaultDisabled advisory parameter

---
 CHANGELOG.md                         |  3 +++
 spec-compliance-matrix.md            |  1 +
 spec-compliance-matrix/cpp.yaml      |  2 ++
 spec-compliance-matrix/dotnet.yaml   |  2 ++
 spec-compliance-matrix/erlang.yaml   |  2 ++
 spec-compliance-matrix/go.yaml       |  2 ++
 spec-compliance-matrix/java.yaml     |  2 ++
 spec-compliance-matrix/js.yaml       |  2 ++
 spec-compliance-matrix/php.yaml      |  2 ++
 spec-compliance-matrix/python.yaml   |  2 ++
 spec-compliance-matrix/ruby.yaml     |  2 ++
 spec-compliance-matrix/rust.yaml     |  2 ++
 spec-compliance-matrix/swift.yaml    |  2 ++
 spec-compliance-matrix/template.yaml |  1 +
 specification/metrics/api.md         | 11 +++++++++++
 specification/metrics/sdk.md         | 21 ++++++++++++++++++---
 16 files changed, 56 insertions(+), 3 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 0bc0648f16a..8ee041845ca 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -13,6 +13,9 @@ release.
 
 ### Metrics
 
+- Add the DefaultDisabled advisory parameter.
+  ([#4809](https://github.com/open-telemetry/opentelemetry-specification/pull/4809))
+
 ### Logs
 
 ### Baggage
diff --git a/spec-compliance-matrix.md b/spec-compliance-matrix.md
index 116a3b786cc..b4952475d83 100644
--- a/spec-compliance-matrix.md
+++ b/spec-compliance-matrix.md
@@ -130,6 +130,7 @@ formats is required. Implementing more than one format is optional.
 | Instrument descriptions conform to the specified syntax. |  | - | + |  | - | + | + |  |  | - | + |  |
 | Instrument supports the advisory ExplicitBucketBoundaries parameter. |  | + | + |  |  |  | + |  |  |  |  |  |
 | Instrument supports the advisory Attributes parameter. |  | - | + |  |  |  | + |  |  |  |  |  |
+| Instrument supports the advisory DefaultDisabled parameter. |  | - | - | - | - | - | - | - | - | - | - | - |
 | All methods of `MeterProvider` are safe to be called concurrently. |  | + | + | + | - |  | + |  |  | + | + |  |
 | All methods of `Meter` are safe to be called concurrently. |  | + | + | + | - |  | + |  |  | + | + |  |
 | All methods of any instrument are safe to be called concurrently. |  | + | + | + | - |  | + |  |  | + | + |  |
diff --git a/spec-compliance-matrix/cpp.yaml b/spec-compliance-matrix/cpp.yaml
index 65ae3abfe76..32ce460a34b 100644
--- a/spec-compliance-matrix/cpp.yaml
+++ b/spec-compliance-matrix/cpp.yaml
@@ -223,6 +223,8 @@ sections:
         status: '?'
       - name: Instrument supports the advisory Attributes parameter.
         status: '?'
+      - name: Instrument supports the advisory DefaultDisabled parameter.
+        status: '-'
       - name: All methods of `MeterProvider` are safe to be called concurrently.
         status: '+'
       - name: All methods of `Meter` are safe to be called concurrently.
diff --git a/spec-compliance-matrix/dotnet.yaml b/spec-compliance-matrix/dotnet.yaml
index f5d51a066d3..68a6b8a2bf0 100644
--- a/spec-compliance-matrix/dotnet.yaml
+++ b/spec-compliance-matrix/dotnet.yaml
@@ -223,6 +223,8 @@ sections:
         status: '?'
       - name: Instrument supports the advisory Attributes parameter.
         status: '?'
+      - name: Instrument supports the advisory DefaultDisabled parameter.
+        status: '-'
       - name: All methods of `MeterProvider` are safe to be called concurrently.
         status: '+'
       - name: All methods of `Meter` are safe to be called concurrently.
diff --git a/spec-compliance-matrix/erlang.yaml b/spec-compliance-matrix/erlang.yaml
index 7d5d680d6a5..da8cf718554 100644
--- a/spec-compliance-matrix/erlang.yaml
+++ b/spec-compliance-matrix/erlang.yaml
@@ -223,6 +223,8 @@ sections:
         status: '+'
       - name: Instrument supports the advisory Attributes parameter.
         status: '+'
+      - name: Instrument supports the advisory DefaultDisabled parameter.
+        status: '-'
       - name: All methods of `MeterProvider` are safe to be called concurrently.
         status: '+'
       - name: All methods of `Meter` are safe to be called concurrently.
diff --git a/spec-compliance-matrix/go.yaml b/spec-compliance-matrix/go.yaml
index 7b3fb26a4b6..d2016ee601a 100644
--- a/spec-compliance-matrix/go.yaml
+++ b/spec-compliance-matrix/go.yaml
@@ -223,6 +223,8 @@ sections:
         status: '+'
       - name: Instrument supports the advisory Attributes parameter.
         status: '-'
+      - name: Instrument supports the advisory DefaultDisabled parameter.
+        status: '-'
       - name: All methods of `MeterProvider` are safe to be called concurrently.
         status: '+'
       - name: All methods of `Meter` are safe to be called concurrently.
diff --git a/spec-compliance-matrix/java.yaml b/spec-compliance-matrix/java.yaml
index e3fe29f9ad3..369e3ce32ab 100644
--- a/spec-compliance-matrix/java.yaml
+++ b/spec-compliance-matrix/java.yaml
@@ -223,6 +223,8 @@ sections:
         status: '+'
       - name: Instrument supports the advisory Attributes parameter.
         status: '+'
+      - name: Instrument supports the advisory DefaultDisabled parameter.
+        status: '-'
       - name: All methods of `MeterProvider` are safe to be called concurrently.
         status: '+'
       - name: All methods of `Meter` are safe to be called concurrently.
diff --git a/spec-compliance-matrix/js.yaml b/spec-compliance-matrix/js.yaml
index a7154980e30..fd4236c6ca8 100644
--- a/spec-compliance-matrix/js.yaml
+++ b/spec-compliance-matrix/js.yaml
@@ -223,6 +223,8 @@ sections:
         status: '?'
       - name: Instrument supports the advisory Attributes parameter.
         status: '?'
+      - name: Instrument supports the advisory DefaultDisabled parameter.
+        status: '-'
       - name: All methods of `MeterProvider` are safe to be called concurrently.
         status: '+'
       - name: All methods of `Meter` are safe to be called concurrently.
diff --git a/spec-compliance-matrix/php.yaml b/spec-compliance-matrix/php.yaml
index 1d506cafd6f..d8e940d7188 100644
--- a/spec-compliance-matrix/php.yaml
+++ b/spec-compliance-matrix/php.yaml
@@ -223,6 +223,8 @@ sections:
         status: '?'
       - name: Instrument supports the advisory Attributes parameter.
         status: '?'
+      - name: Instrument supports the advisory DefaultDisabled parameter.
+        status: '-'
       - name: All methods of `MeterProvider` are safe to be called concurrently.
         status: '?'
       - name: All methods of `Meter` are safe to be called concurrently.
diff --git a/spec-compliance-matrix/python.yaml b/spec-compliance-matrix/python.yaml
index 9c686be08a1..638cc5ce1d0 100644
--- a/spec-compliance-matrix/python.yaml
+++ b/spec-compliance-matrix/python.yaml
@@ -223,6 +223,8 @@ sections:
         status: '?'
       - name: Instrument supports the advisory Attributes parameter.
         status: '?'
+      - name: Instrument supports the advisory DefaultDisabled parameter.
+        status: '-'
       - name: All methods of `MeterProvider` are safe to be called concurrently.
         status: '-'
       - name: All methods of `Meter` are safe to be called concurrently.
diff --git a/spec-compliance-matrix/ruby.yaml b/spec-compliance-matrix/ruby.yaml
index 0c690c00109..a7d1b47e4ba 100644
--- a/spec-compliance-matrix/ruby.yaml
+++ b/spec-compliance-matrix/ruby.yaml
@@ -223,6 +223,8 @@ sections:
         status: '?'
       - name: Instrument supports the advisory Attributes parameter.
         status: '?'
+      - name: Instrument supports the advisory DefaultDisabled parameter.
+        status: '-'
       - name: All methods of `MeterProvider` are safe to be called concurrently.
         status: '?'
       - name: All methods of `Meter` are safe to be called concurrently.
diff --git a/spec-compliance-matrix/rust.yaml b/spec-compliance-matrix/rust.yaml
index 1f3cb6913f3..f0e8ac6bbc5 100644
--- a/spec-compliance-matrix/rust.yaml
+++ b/spec-compliance-matrix/rust.yaml
@@ -223,6 +223,8 @@ sections:
         status: '?'
       - name: Instrument supports the advisory Attributes parameter.
         status: '?'
+      - name: Instrument supports the advisory DefaultDisabled parameter.
+        status: '-'
       - name: All methods of `MeterProvider` are safe to be called concurrently.
         status: '?'
       - name: All methods of `Meter` are safe to be called concurrently.
diff --git a/spec-compliance-matrix/swift.yaml b/spec-compliance-matrix/swift.yaml
index 5ff118465d6..08ea49b804a 100644
--- a/spec-compliance-matrix/swift.yaml
+++ b/spec-compliance-matrix/swift.yaml
@@ -223,6 +223,8 @@ sections:
         status: '?'
       - name: Instrument supports the advisory Attributes parameter.
         status: '?'
+      - name: Instrument supports the advisory DefaultDisabled parameter.
+        status: '-'
       - name: All methods of `MeterProvider` are safe to be called concurrently.
         status: '?'
       - name: All methods of `Meter` are safe to be called concurrently.
diff --git a/spec-compliance-matrix/template.yaml b/spec-compliance-matrix/template.yaml
index 3013f98e178..e0fcfdcae40 100644
--- a/spec-compliance-matrix/template.yaml
+++ b/spec-compliance-matrix/template.yaml
@@ -155,6 +155,7 @@ sections:
       - name: Instrument descriptions conform to the specified syntax.
       - name: Instrument supports the advisory ExplicitBucketBoundaries parameter.
       - name: Instrument supports the advisory Attributes parameter.
+      - name: Instrument supports the advisory DefaultDisabled parameter.
       - name: All methods of `MeterProvider` are safe to be called concurrently.
       - name: All methods of `Meter` are safe to be called concurrently.
       - name: All methods of any instrument are safe to be called concurrently.
diff --git a/specification/metrics/api.md b/specification/metrics/api.md
index c37fccc944d..0197015e8dd 100644
--- a/specification/metrics/api.md
+++ b/specification/metrics/api.md
@@ -26,6 +26,7 @@ weight: 1
     + [Instrument advisory parameters](#instrument-advisory-parameters)
       - [Instrument advisory parameter: `ExplicitBucketBoundaries`](#instrument-advisory-parameter-explicitbucketboundaries)
       - [Instrument advisory parameter: `Attributes`](#instrument-advisory-parameter-attributes)
+      - [Instrument advisory parameter: `DefaultDisabled`](#instrument-advisory-parameter-defaultdisabled)
     + [Synchronous and Asynchronous instruments](#synchronous-and-asynchronous-instruments)
       - [Synchronous Instrument API](#synchronous-instrument-api)
       - [Asynchronous Instrument API](#asynchronous-instrument-api)
@@ -276,6 +277,16 @@ Applies to all instrument types.
 `Attributes` (a list of [attribute keys](../common/README.md#attribute)) is
 the recommended set of attribute keys to be used for the resulting metrics.
 
+##### Instrument advisory parameter: `DefaultDisabled`
+
+**Status**: [Development](../document-status.md)
+
+Applies to all instrument types.
+
+`DefaultDisabled` indicates that the instrument should not produce metric data
+and functions on the instrument should be no-ops unless the user has explicitly
+enabled the metric.
+
 #### Synchronous and Asynchronous instruments
 
 Instruments are categorized on whether they are synchronous or
diff --git a/specification/metrics/sdk.md b/specification/metrics/sdk.md
index 0c3da4b83fc..d0473b03d7d 100644
--- a/specification/metrics/sdk.md
+++ b/specification/metrics/sdk.md
@@ -52,6 +52,7 @@ weight: 3
   * [Instrument advisory parameters](#instrument-advisory-parameters)
     + [Instrument advisory parameter: `ExplicitBucketBoundaries`](#instrument-advisory-parameter-explicitbucketboundaries)
     + [Instrument advisory parameter: `Attributes`](#instrument-advisory-parameter-attributes)
+    + [Instrument advisory parameter: `DefaultDisabled`](#instrument-advisory-parameter-defaultdisabled)
   * [Instrument enabled](#instrument-enabled)
 - [Attribute limits](#attribute-limits)
 - [Exemplar](#exemplar)
@@ -420,9 +421,13 @@ The SDK SHOULD use the following logic to determine how to process Measurements
 made with an Instrument:
 
 * Determine the `MeterProvider` which "owns" the Instrument.
-* If the `MeterProvider` has no `View` registered, take the Instrument
-    and apply the default Aggregation on the basis of instrument kind according
-    to the [MetricReader](#metricreader) instance's `aggregation` property.
+* If the `MeterProvider` has no `View` registered:
+  * **Status**: [Development](../document-status.md) - If the instrument's
+    [DefaultDisabled advisory parameter](#instrument-advisory-parameter-defaultdisabled)
+    is set, use the [Drop Aggregation](#drop-aggregation).
+  * If DefaultDisabled is not set, take the Instrument and apply the default
+    Aggregation on the basis of instrument kind according to the
+    [MetricReader](#metricreader) instance's `aggregation` property.
     [Instrument advisory parameters](#instrument-advisory-parameters), if any,
     MUST be honored.
 * If the `MeterProvider` has one or more `View`(s) registered:
@@ -999,6 +1004,16 @@ If no View is configured, or if a matching view does not specify attribute keys,
 the advisory parameter should be used. If neither is provided, all attributes
 must be retained.
 
+#### Instrument advisory parameter: `DefaultDisabled`
+
+**Status**: [Development](../document-status.md)
+
+This advisory parameter applies to all aggregations.
+
+When an instrument is `DefaultDisabled`, the SDK MUST use the
+[Drop Aggregation](#drop-aggregation) by default. If the user has provided an
+Aggregation via View(s), that aggregation takes precedence.
+
 ### Instrument enabled
 
 The synchronous instrument [`Enabled`](./api.md#enabled) MUST return `false`

From 03cbc8090cae60bdcd34857e0a40ec3bdaeedb96 Mon Sep 17 00:00:00 2001
From: David Ashpole <dashpole@google.com>
Date: Tue, 16 Dec 2025 21:55:06 +0000
Subject: [PATCH 02/12] make bool explicit

---
 specification/metrics/api.md | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/specification/metrics/api.md b/specification/metrics/api.md
index 0197015e8dd..260a49f7e66 100644
--- a/specification/metrics/api.md
+++ b/specification/metrics/api.md
@@ -283,9 +283,9 @@ the recommended set of attribute keys to be used for the resulting metrics.
 
 Applies to all instrument types.
 
-`DefaultDisabled` indicates that the instrument should not produce metric data
-and functions on the instrument should be no-ops unless the user has explicitly
-enabled the metric.
+`DefaultDisabled` (bool) if true, indicates that the instrument should not
+produce metric data and that functions on the instrument should be no-ops
+unless the user has explicitly enabled the metric.
 
 #### Synchronous and Asynchronous instruments
 

From 2e3fbd2922c6108e8f1c4e42e460932ec84a2376 Mon Sep 17 00:00:00 2001
From: David Ashpole <dashpole@google.com>
Date: Mon, 5 Jan 2026 21:08:19 +0000
Subject: [PATCH 03/12] rename to OptIn

---
 CHANGELOG.md                         |  2 +-
 spec-compliance-matrix.md            |  2 +-
 spec-compliance-matrix/cpp.yaml      |  2 +-
 spec-compliance-matrix/dotnet.yaml   |  2 +-
 spec-compliance-matrix/erlang.yaml   |  2 +-
 spec-compliance-matrix/go.yaml       |  2 +-
 spec-compliance-matrix/java.yaml     |  2 +-
 spec-compliance-matrix/js.yaml       |  2 +-
 spec-compliance-matrix/php.yaml      |  2 +-
 spec-compliance-matrix/python.yaml   |  2 +-
 spec-compliance-matrix/ruby.yaml     |  2 +-
 spec-compliance-matrix/rust.yaml     |  2 +-
 spec-compliance-matrix/swift.yaml    |  2 +-
 spec-compliance-matrix/template.yaml |  2 +-
 specification/metrics/api.md         |  6 +++---
 specification/metrics/sdk.md         | 12 ++++++------
 16 files changed, 23 insertions(+), 23 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 8ee041845ca..93072979516 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -13,7 +13,7 @@ release.
 
 ### Metrics
 
-- Add the DefaultDisabled advisory parameter.
+- Add the OptIn advisory parameter.
   ([#4809](https://github.com/open-telemetry/opentelemetry-specification/pull/4809))
 
 ### Logs
diff --git a/spec-compliance-matrix.md b/spec-compliance-matrix.md
index b4952475d83..23cc47f9d94 100644
--- a/spec-compliance-matrix.md
+++ b/spec-compliance-matrix.md
@@ -130,7 +130,7 @@ formats is required. Implementing more than one format is optional.
 | Instrument descriptions conform to the specified syntax. |  | - | + |  | - | + | + |  |  | - | + |  |
 | Instrument supports the advisory ExplicitBucketBoundaries parameter. |  | + | + |  |  |  | + |  |  |  |  |  |
 | Instrument supports the advisory Attributes parameter. |  | - | + |  |  |  | + |  |  |  |  |  |
-| Instrument supports the advisory DefaultDisabled parameter. |  | - | - | - | - | - | - | - | - | - | - | - |
+| Instrument supports the advisory OptIn parameter. |  | - | - | - | - | - | - | - | - | - | - | - |
 | All methods of `MeterProvider` are safe to be called concurrently. |  | + | + | + | - |  | + |  |  | + | + |  |
 | All methods of `Meter` are safe to be called concurrently. |  | + | + | + | - |  | + |  |  | + | + |  |
 | All methods of any instrument are safe to be called concurrently. |  | + | + | + | - |  | + |  |  | + | + |  |
diff --git a/spec-compliance-matrix/cpp.yaml b/spec-compliance-matrix/cpp.yaml
index 32ce460a34b..cba61a615ac 100644
--- a/spec-compliance-matrix/cpp.yaml
+++ b/spec-compliance-matrix/cpp.yaml
@@ -223,7 +223,7 @@ sections:
         status: '?'
       - name: Instrument supports the advisory Attributes parameter.
         status: '?'
-      - name: Instrument supports the advisory DefaultDisabled parameter.
+      - name: Instrument supports the advisory OptIn parameter.
         status: '-'
       - name: All methods of `MeterProvider` are safe to be called concurrently.
         status: '+'
diff --git a/spec-compliance-matrix/dotnet.yaml b/spec-compliance-matrix/dotnet.yaml
index 68a6b8a2bf0..da8a933b50b 100644
--- a/spec-compliance-matrix/dotnet.yaml
+++ b/spec-compliance-matrix/dotnet.yaml
@@ -223,7 +223,7 @@ sections:
         status: '?'
       - name: Instrument supports the advisory Attributes parameter.
         status: '?'
-      - name: Instrument supports the advisory DefaultDisabled parameter.
+      - name: Instrument supports the advisory OptIn parameter.
         status: '-'
       - name: All methods of `MeterProvider` are safe to be called concurrently.
         status: '+'
diff --git a/spec-compliance-matrix/erlang.yaml b/spec-compliance-matrix/erlang.yaml
index da8cf718554..e42d3231bef 100644
--- a/spec-compliance-matrix/erlang.yaml
+++ b/spec-compliance-matrix/erlang.yaml
@@ -223,7 +223,7 @@ sections:
         status: '+'
       - name: Instrument supports the advisory Attributes parameter.
         status: '+'
-      - name: Instrument supports the advisory DefaultDisabled parameter.
+      - name: Instrument supports the advisory OptIn parameter.
         status: '-'
       - name: All methods of `MeterProvider` are safe to be called concurrently.
         status: '+'
diff --git a/spec-compliance-matrix/go.yaml b/spec-compliance-matrix/go.yaml
index d2016ee601a..c79d6474093 100644
--- a/spec-compliance-matrix/go.yaml
+++ b/spec-compliance-matrix/go.yaml
@@ -223,7 +223,7 @@ sections:
         status: '+'
       - name: Instrument supports the advisory Attributes parameter.
         status: '-'
-      - name: Instrument supports the advisory DefaultDisabled parameter.
+      - name: Instrument supports the advisory OptIn parameter.
         status: '-'
       - name: All methods of `MeterProvider` are safe to be called concurrently.
         status: '+'
diff --git a/spec-compliance-matrix/java.yaml b/spec-compliance-matrix/java.yaml
index 369e3ce32ab..33fec46a511 100644
--- a/spec-compliance-matrix/java.yaml
+++ b/spec-compliance-matrix/java.yaml
@@ -223,7 +223,7 @@ sections:
         status: '+'
       - name: Instrument supports the advisory Attributes parameter.
         status: '+'
-      - name: Instrument supports the advisory DefaultDisabled parameter.
+      - name: Instrument supports the advisory OptIn parameter.
         status: '-'
       - name: All methods of `MeterProvider` are safe to be called concurrently.
         status: '+'
diff --git a/spec-compliance-matrix/js.yaml b/spec-compliance-matrix/js.yaml
index fd4236c6ca8..3739111b8b0 100644
--- a/spec-compliance-matrix/js.yaml
+++ b/spec-compliance-matrix/js.yaml
@@ -223,7 +223,7 @@ sections:
         status: '?'
       - name: Instrument supports the advisory Attributes parameter.
         status: '?'
-      - name: Instrument supports the advisory DefaultDisabled parameter.
+      - name: Instrument supports the advisory OptIn parameter.
         status: '-'
       - name: All methods of `MeterProvider` are safe to be called concurrently.
         status: '+'
diff --git a/spec-compliance-matrix/php.yaml b/spec-compliance-matrix/php.yaml
index d8e940d7188..8e7587015ce 100644
--- a/spec-compliance-matrix/php.yaml
+++ b/spec-compliance-matrix/php.yaml
@@ -223,7 +223,7 @@ sections:
         status: '?'
       - name: Instrument supports the advisory Attributes parameter.
         status: '?'
-      - name: Instrument supports the advisory DefaultDisabled parameter.
+      - name: Instrument supports the advisory OptIn parameter.
         status: '-'
       - name: All methods of `MeterProvider` are safe to be called concurrently.
         status: '?'
diff --git a/spec-compliance-matrix/python.yaml b/spec-compliance-matrix/python.yaml
index 638cc5ce1d0..592a02cf991 100644
--- a/spec-compliance-matrix/python.yaml
+++ b/spec-compliance-matrix/python.yaml
@@ -223,7 +223,7 @@ sections:
         status: '?'
       - name: Instrument supports the advisory Attributes parameter.
         status: '?'
-      - name: Instrument supports the advisory DefaultDisabled parameter.
+      - name: Instrument supports the advisory OptIn parameter.
         status: '-'
       - name: All methods of `MeterProvider` are safe to be called concurrently.
         status: '-'
diff --git a/spec-compliance-matrix/ruby.yaml b/spec-compliance-matrix/ruby.yaml
index a7d1b47e4ba..7acb5e6a3d3 100644
--- a/spec-compliance-matrix/ruby.yaml
+++ b/spec-compliance-matrix/ruby.yaml
@@ -223,7 +223,7 @@ sections:
         status: '?'
       - name: Instrument supports the advisory Attributes parameter.
         status: '?'
-      - name: Instrument supports the advisory DefaultDisabled parameter.
+      - name: Instrument supports the advisory OptIn parameter.
         status: '-'
       - name: All methods of `MeterProvider` are safe to be called concurrently.
         status: '?'
diff --git a/spec-compliance-matrix/rust.yaml b/spec-compliance-matrix/rust.yaml
index f0e8ac6bbc5..c85d7f1eebb 100644
--- a/spec-compliance-matrix/rust.yaml
+++ b/spec-compliance-matrix/rust.yaml
@@ -223,7 +223,7 @@ sections:
         status: '?'
       - name: Instrument supports the advisory Attributes parameter.
         status: '?'
-      - name: Instrument supports the advisory DefaultDisabled parameter.
+      - name: Instrument supports the advisory OptIn parameter.
         status: '-'
       - name: All methods of `MeterProvider` are safe to be called concurrently.
         status: '?'
diff --git a/spec-compliance-matrix/swift.yaml b/spec-compliance-matrix/swift.yaml
index 08ea49b804a..5dde92f7475 100644
--- a/spec-compliance-matrix/swift.yaml
+++ b/spec-compliance-matrix/swift.yaml
@@ -223,7 +223,7 @@ sections:
         status: '?'
       - name: Instrument supports the advisory Attributes parameter.
         status: '?'
-      - name: Instrument supports the advisory DefaultDisabled parameter.
+      - name: Instrument supports the advisory OptIn parameter.
         status: '-'
       - name: All methods of `MeterProvider` are safe to be called concurrently.
         status: '?'
diff --git a/spec-compliance-matrix/template.yaml b/spec-compliance-matrix/template.yaml
index e0fcfdcae40..ac6fba7c328 100644
--- a/spec-compliance-matrix/template.yaml
+++ b/spec-compliance-matrix/template.yaml
@@ -155,7 +155,7 @@ sections:
       - name: Instrument descriptions conform to the specified syntax.
       - name: Instrument supports the advisory ExplicitBucketBoundaries parameter.
       - name: Instrument supports the advisory Attributes parameter.
-      - name: Instrument supports the advisory DefaultDisabled parameter.
+      - name: Instrument supports the advisory OptIn parameter.
       - name: All methods of `MeterProvider` are safe to be called concurrently.
       - name: All methods of `Meter` are safe to be called concurrently.
       - name: All methods of any instrument are safe to be called concurrently.
diff --git a/specification/metrics/api.md b/specification/metrics/api.md
index 260a49f7e66..bd50816a058 100644
--- a/specification/metrics/api.md
+++ b/specification/metrics/api.md
@@ -26,7 +26,7 @@ weight: 1
     + [Instrument advisory parameters](#instrument-advisory-parameters)
       - [Instrument advisory parameter: `ExplicitBucketBoundaries`](#instrument-advisory-parameter-explicitbucketboundaries)
       - [Instrument advisory parameter: `Attributes`](#instrument-advisory-parameter-attributes)
-      - [Instrument advisory parameter: `DefaultDisabled`](#instrument-advisory-parameter-defaultdisabled)
+      - [Instrument advisory parameter: `OptIn`](#instrument-advisory-parameter-optin)
     + [Synchronous and Asynchronous instruments](#synchronous-and-asynchronous-instruments)
       - [Synchronous Instrument API](#synchronous-instrument-api)
       - [Asynchronous Instrument API](#asynchronous-instrument-api)
@@ -277,13 +277,13 @@ Applies to all instrument types.
 `Attributes` (a list of [attribute keys](../common/README.md#attribute)) is
 the recommended set of attribute keys to be used for the resulting metrics.
 
-##### Instrument advisory parameter: `DefaultDisabled`
+##### Instrument advisory parameter: `OptIn`
 
 **Status**: [Development](../document-status.md)
 
 Applies to all instrument types.
 
-`DefaultDisabled` (bool) if true, indicates that the instrument should not
+`OptIn` (bool) if true, indicates that the instrument should not
 produce metric data and that functions on the instrument should be no-ops
 unless the user has explicitly enabled the metric.
 
diff --git a/specification/metrics/sdk.md b/specification/metrics/sdk.md
index d0473b03d7d..c2ac40d7af8 100644
--- a/specification/metrics/sdk.md
+++ b/specification/metrics/sdk.md
@@ -52,7 +52,7 @@ weight: 3
   * [Instrument advisory parameters](#instrument-advisory-parameters)
     + [Instrument advisory parameter: `ExplicitBucketBoundaries`](#instrument-advisory-parameter-explicitbucketboundaries)
     + [Instrument advisory parameter: `Attributes`](#instrument-advisory-parameter-attributes)
-    + [Instrument advisory parameter: `DefaultDisabled`](#instrument-advisory-parameter-defaultdisabled)
+    + [Instrument advisory parameter: `OptIn`](#instrument-advisory-parameter-OptIn)
   * [Instrument enabled](#instrument-enabled)
 - [Attribute limits](#attribute-limits)
 - [Exemplar](#exemplar)
@@ -423,9 +423,9 @@ made with an Instrument:
 * Determine the `MeterProvider` which "owns" the Instrument.
 * If the `MeterProvider` has no `View` registered:
   * **Status**: [Development](../document-status.md) - If the instrument's
-    [DefaultDisabled advisory parameter](#instrument-advisory-parameter-defaultdisabled)
-    is set, use the [Drop Aggregation](#drop-aggregation).
-  * If DefaultDisabled is not set, take the Instrument and apply the default
+    [OptIn advisory parameter](#instrument-advisory-parameter-OptIn)
+    is set to true, use the [Drop Aggregation](#drop-aggregation).
+  * If OptIn is false, take the Instrument and apply the default
     Aggregation on the basis of instrument kind according to the
     [MetricReader](#metricreader) instance's `aggregation` property.
     [Instrument advisory parameters](#instrument-advisory-parameters), if any,
@@ -1004,13 +1004,13 @@ If no View is configured, or if a matching view does not specify attribute keys,
 the advisory parameter should be used. If neither is provided, all attributes
 must be retained.
 
-#### Instrument advisory parameter: `DefaultDisabled`
+#### Instrument advisory parameter: `OptIn`
 
 **Status**: [Development](../document-status.md)
 
 This advisory parameter applies to all aggregations.
 
-When an instrument is `DefaultDisabled`, the SDK MUST use the
+When an instrument is `OptIn`, the SDK MUST use the
 [Drop Aggregation](#drop-aggregation) by default. If the user has provided an
 Aggregation via View(s), that aggregation takes precedence.
 

From 37821ea404e467ebd39709e15a244cd2c465e722 Mon Sep 17 00:00:00 2001
From: David Ashpole <dashpole@google.com>
Date: Mon, 5 Jan 2026 21:37:02 +0000
Subject: [PATCH 04/12] clarify that advisory parameters apply when views are
 registered, but don't match

---
 specification/metrics/sdk.md | 45 ++++++++++++++++++------------------
 1 file changed, 22 insertions(+), 23 deletions(-)

diff --git a/specification/metrics/sdk.md b/specification/metrics/sdk.md
index c2ac40d7af8..f8587e28f57 100644
--- a/specification/metrics/sdk.md
+++ b/specification/metrics/sdk.md
@@ -421,7 +421,8 @@ The SDK SHOULD use the following logic to determine how to process Measurements
 made with an Instrument:
 
 * Determine the `MeterProvider` which "owns" the Instrument.
-* If the `MeterProvider` has no `View` registered:
+* If the `MeterProvider` has no `View` registered, or if the Instrument does
+  not match any View's instrument selection criteria:
   * **Status**: [Development](../document-status.md) - If the instrument's
     [OptIn advisory parameter](#instrument-advisory-parameter-OptIn)
     is set to true, use the [Drop Aggregation](#drop-aggregation).
@@ -430,28 +431,26 @@ made with an Instrument:
     [MetricReader](#metricreader) instance's `aggregation` property.
     [Instrument advisory parameters](#instrument-advisory-parameters), if any,
     MUST be honored.
-* If the `MeterProvider` has one or more `View`(s) registered:
-  * If the Instrument could match the instrument selection criteria, for each
-    View:
-    * Try to apply the View's stream configuration independently of any other
-      Views registered for the same matching Instrument (i.e. Views are not
-      merged). This may result in [conflicting metric identities](./data-model.md#opentelemetry-protocol-data-model-producer-recommendations)
-      even if stream configurations specify non-overlapping properties (e.g.
-      one View setting `aggregation` and another View setting `attribute_keys`,
-      both leaving the stream `name` as the default configured by the
-      Instrument). If applying the View results in conflicting metric identities
-      the implementation SHOULD apply the View and emit a warning. If it is not
-      possible to apply the View without producing semantic errors (e.g. the
-      View sets an asynchronous instrument to use the [Explicit bucket
-      histogram aggregation](#explicit-bucket-histogram-aggregation)) the
-      implementation SHOULD emit a warning and proceed as if the View did not
-      If both a View and [Instrument advisory parameters](#instrument-advisory-parameters)
-      specify the same aspect of the [Stream configuration](#stream-configuration),
-      the setting defined by the View MUST take precedence over the advisory parameters.
-  * If the Instrument could not match with any of the registered `View`(s), the
-    SDK SHOULD enable the instrument using the default aggregation and temporality.
-    Users can configure match-all Views using [Drop aggregation](#drop-aggregation)
-    to disable instruments by default.
+* If the `MeterProvider` has one or more matching `View`(s) registered, for
+  each `View` that matches the instrument selection criteria:
+  * Try to apply the View's stream configuration independently of any other
+    Views registered for the same matching Instrument (i.e. Views are not
+    merged). This may result in [conflicting metric identities](./data-model.md#opentelemetry-protocol-data-model-producer-recommendations)
+    even if stream configurations specify non-overlapping properties (e.g.
+    one View setting `aggregation` and another View setting `attribute_keys`,
+    both leaving the stream `name` as the default configured by the
+    Instrument). If applying the View results in conflicting metric identities
+    the implementation SHOULD apply the View and emit a warning. If it is not
+    possible to apply the View without producing semantic errors (e.g. the
+    View sets an asynchronous instrument to use the [Explicit bucket
+    histogram aggregation](#explicit-bucket-histogram-aggregation)) the
+    implementation SHOULD emit a warning and proceed as if the View did not
+    If both a View and [Instrument advisory parameters](#instrument-advisory-parameters)
+    specify the same aspect of the [Stream configuration](#stream-configuration),
+    the setting defined by the View MUST take precedence over the advisory parameters.
+
+Users can configure match-all Views using [Drop aggregation](#drop-aggregation)
+to disable instruments by default.
 
 #### View examples
 

From fb933a879330d29f200cee61d4ef67af44f6c6fe Mon Sep 17 00:00:00 2001
From: David Ashpole <dashpole@google.com>
Date: Mon, 5 Jan 2026 21:41:50 +0000
Subject: [PATCH 05/12] fix lint

---
 specification/metrics/sdk.md | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/specification/metrics/sdk.md b/specification/metrics/sdk.md
index f8587e28f57..0d70e86fbe1 100644
--- a/specification/metrics/sdk.md
+++ b/specification/metrics/sdk.md
@@ -52,7 +52,7 @@ weight: 3
   * [Instrument advisory parameters](#instrument-advisory-parameters)
     + [Instrument advisory parameter: `ExplicitBucketBoundaries`](#instrument-advisory-parameter-explicitbucketboundaries)
     + [Instrument advisory parameter: `Attributes`](#instrument-advisory-parameter-attributes)
-    + [Instrument advisory parameter: `OptIn`](#instrument-advisory-parameter-OptIn)
+    + [Instrument advisory parameter: `OptIn`](#instrument-advisory-parameter-optin)
   * [Instrument enabled](#instrument-enabled)
 - [Attribute limits](#attribute-limits)
 - [Exemplar](#exemplar)
@@ -424,7 +424,7 @@ made with an Instrument:
 * If the `MeterProvider` has no `View` registered, or if the Instrument does
   not match any View's instrument selection criteria:
   * **Status**: [Development](../document-status.md) - If the instrument's
-    [OptIn advisory parameter](#instrument-advisory-parameter-OptIn)
+    [OptIn advisory parameter](#instrument-advisory-parameter-optin)
     is set to true, use the [Drop Aggregation](#drop-aggregation).
   * If OptIn is false, take the Instrument and apply the default
     Aggregation on the basis of instrument kind according to the

From d6471063854aca901c1423b38944c1434f615b4a Mon Sep 17 00:00:00 2001
From: David Ashpole <dashpole@google.com>
Date: Tue, 6 Jan 2026 10:27:48 -0500
Subject: [PATCH 06/12] Update specification/metrics/api.md

Co-authored-by: Tyler Yahn <MrAlias@users.noreply.github.com>
---
 specification/metrics/api.md | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/specification/metrics/api.md b/specification/metrics/api.md
index bd50816a058..7439b6ab9d4 100644
--- a/specification/metrics/api.md
+++ b/specification/metrics/api.md
@@ -283,8 +283,8 @@ the recommended set of attribute keys to be used for the resulting metrics.
 
 Applies to all instrument types.
 
-`OptIn` (bool) if true, indicates that the instrument should not
-produce metric data and that functions on the instrument should be no-ops
+`OptIn` (bool) if true, indicates that the instrument MUST NOT
+produce metric data and that functions on the instrument SHOULD be no-ops
 unless the user has explicitly enabled the metric.
 
 #### Synchronous and Asynchronous instruments

From 23bcef0fe26951fd9b478bbeeb9c5da0b6d8be1b Mon Sep 17 00:00:00 2001
From: David Ashpole <dashpole@google.com>
Date: Tue, 6 Jan 2026 21:26:22 +0000
Subject: [PATCH 07/12] clarify that the defualt aggregation enables OptIn
 instruments

---
 specification/metrics/sdk.md | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/specification/metrics/sdk.md b/specification/metrics/sdk.md
index 0d70e86fbe1..c8e2aac37ae 100644
--- a/specification/metrics/sdk.md
+++ b/specification/metrics/sdk.md
@@ -1011,7 +1011,10 @@ This advisory parameter applies to all aggregations.
 
 When an instrument is `OptIn`, the SDK MUST use the
 [Drop Aggregation](#drop-aggregation) by default. If the user has provided an
-Aggregation via View(s), that aggregation takes precedence.
+Aggregation via View(s), that aggregation takes precedence. If the user
+provides the [Default Aggregation](#default-aggregation) using a View, this
+"enables" the instrument with the same behavior as-if the instrument was not
+`OptIn`--including respecting other advisory parameters.
 
 ### Instrument enabled
 

From 5929f555fe8dff00ec14a4279c6a515a286e8605 Mon Sep 17 00:00:00 2001
From: David Ashpole <dashpole@google.com>
Date: Thu, 8 Jan 2026 11:32:05 -0500
Subject: [PATCH 08/12] Update specification/metrics/sdk.md

Co-authored-by: Cijo Thomas <cithomas@microsoft.com>
---
 specification/metrics/sdk.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/specification/metrics/sdk.md b/specification/metrics/sdk.md
index c8e2aac37ae..98d74190f6c 100644
--- a/specification/metrics/sdk.md
+++ b/specification/metrics/sdk.md
@@ -1009,7 +1009,7 @@ must be retained.
 
 This advisory parameter applies to all aggregations.
 
-When an instrument is `OptIn`, the SDK MUST use the
+When an instrument has `OptIn=true`, the SDK MUST use the
 [Drop Aggregation](#drop-aggregation) by default. If the user has provided an
 Aggregation via View(s), that aggregation takes precedence. If the user
 provides the [Default Aggregation](#default-aggregation) using a View, this

From e79e34fcb43d8b03d784fde3a8237ea8385c5639 Mon Sep 17 00:00:00 2001
From: David Ashpole <dashpole@google.com>
Date: Thu, 8 Jan 2026 20:53:10 +0000
Subject: [PATCH 09/12] add explicit enabled field to view configuration

---
 specification/metrics/sdk.md | 20 +++++++++++++-------
 1 file changed, 13 insertions(+), 7 deletions(-)

diff --git a/specification/metrics/sdk.md b/specification/metrics/sdk.md
index 98d74190f6c..3696b61390f 100644
--- a/specification/metrics/sdk.md
+++ b/specification/metrics/sdk.md
@@ -414,6 +414,11 @@ The SDK MUST accept the following stream configuration parameters:
   `aggregation_cardinality_limit` value, the `MeterProvider` MUST apply the
   [default aggregation cardinality limit](#metricreader) the `MetricReader` is
   configured with.
+* **Status**: [Development](../document-status.md) - `enabled` (optional): A
+  boolean denoting whether the instrument should be enabled. When `enabled` is
+  `false`, the View uses the `DropAggregation`, regardless of the `aggregation`
+  provided. If unset, the default is `true` unless the `OptIn` 
+  parameter is `true`.
 
 #### Measurement processing
 
@@ -449,8 +454,8 @@ made with an Instrument:
     specify the same aspect of the [Stream configuration](#stream-configuration),
     the setting defined by the View MUST take precedence over the advisory parameters.
 
-Users can configure match-all Views using [Drop aggregation](#drop-aggregation)
-to disable instruments by default.
+Users can configure match-all Views with `enabled=false` or with the
+[Drop aggregation](#drop-aggregation), to disable instruments by default.
 
 #### View examples
 
@@ -1010,11 +1015,12 @@ must be retained.
 This advisory parameter applies to all aggregations.
 
 When an instrument has `OptIn=true`, the SDK MUST use the
-[Drop Aggregation](#drop-aggregation) by default. If the user has provided an
-Aggregation via View(s), that aggregation takes precedence. If the user
-provides the [Default Aggregation](#default-aggregation) using a View, this
-"enables" the instrument with the same behavior as-if the instrument was not
-`OptIn`--including respecting other advisory parameters.
+[Drop Aggregation](#drop-aggregation). If the user sets `enabled=true` on a
+View's [Stream configuration](#stream-configuration), this "enables" the
+instrument with the same behavior as-if the instrument was not `OptIn` --
+including respecting other advisory parameters. Setting fields other than
+`enabled` on the View, including setting the `aggregation`, does not enable
+the instrument.
 
 ### Instrument enabled
 

From 7899e97b02d40cfc9f010ef1e0d3773803483d2d Mon Sep 17 00:00:00 2001
From: David Ashpole <dashpole@google.com>
Date: Thu, 8 Jan 2026 20:55:13 +0000
Subject: [PATCH 10/12] address wording feedback

---
 specification/metrics/sdk.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/specification/metrics/sdk.md b/specification/metrics/sdk.md
index 3696b61390f..af8c520b881 100644
--- a/specification/metrics/sdk.md
+++ b/specification/metrics/sdk.md
@@ -1017,7 +1017,7 @@ This advisory parameter applies to all aggregations.
 When an instrument has `OptIn=true`, the SDK MUST use the
 [Drop Aggregation](#drop-aggregation). If the user sets `enabled=true` on a
 View's [Stream configuration](#stream-configuration), this "enables" the
-instrument with the same behavior as-if the instrument was not `OptIn` --
+instrument with the same behavior as-if the instrument was `OptIn=false` --
 including respecting other advisory parameters. Setting fields other than
 `enabled` on the View, including setting the `aggregation`, does not enable
 the instrument.

From 9a96262eb252a93fe6c28f29c424d2edfd42e294 Mon Sep 17 00:00:00 2001
From: David Ashpole <dashpole@google.com>
Date: Thu, 8 Jan 2026 20:59:04 +0000
Subject: [PATCH 11/12] lint

---
 specification/metrics/sdk.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/specification/metrics/sdk.md b/specification/metrics/sdk.md
index af8c520b881..8b281351291 100644
--- a/specification/metrics/sdk.md
+++ b/specification/metrics/sdk.md
@@ -417,7 +417,7 @@ The SDK MUST accept the following stream configuration parameters:
 * **Status**: [Development](../document-status.md) - `enabled` (optional): A
   boolean denoting whether the instrument should be enabled. When `enabled` is
   `false`, the View uses the `DropAggregation`, regardless of the `aggregation`
-  provided. If unset, the default is `true` unless the `OptIn` 
+  provided. If unset, the default is `true` unless the `OptIn`
   parameter is `true`.
 
 #### Measurement processing

From 6805ae295c478555983534c81002e17fceaa7124 Mon Sep 17 00:00:00 2001
From: David Ashpole <dashpole@google.com>
Date: Wed, 28 Jan 2026 17:14:45 +0000
Subject: [PATCH 12/12] view stream.Enabled can be unset

---
 specification/metrics/sdk.md | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/specification/metrics/sdk.md b/specification/metrics/sdk.md
index 8b281351291..96f5edccbf8 100644
--- a/specification/metrics/sdk.md
+++ b/specification/metrics/sdk.md
@@ -417,8 +417,10 @@ The SDK MUST accept the following stream configuration parameters:
 * **Status**: [Development](../document-status.md) - `enabled` (optional): A
   boolean denoting whether the instrument should be enabled. When `enabled` is
   `false`, the View uses the `DropAggregation`, regardless of the `aggregation`
-  provided. If unset, the default is `true` unless the `OptIn`
-  parameter is `true`.
+  provided. When `enabled` is `true` for an instrument with `OptIn` set to
+  `true`, the SDK treats the instrument as-if `OptIn` was set to false. The
+  SDK must allow `enabled` to be unset (neither true nor false). If unset,
+  `enabled` has no effect.
 
 #### Measurement processing