diff --git a/.github/CODEOWNERS b/.github/CODEOWNERS
index 522b35d2f..135d78043 100644
--- a/.github/CODEOWNERS
+++ b/.github/CODEOWNERS
@@ -16,5 +16,5 @@
 *   @open-telemetry/spec-sponsors
 
 # Profiles owners (global + profiles)
-opentelemetry/proto/profiles  @open-telemetry/spec-sponsors @open-telemetry/profiling-maintainers @open-telemetry/profiling-approvers
-opentelemetry/proto/collector/profiles  @open-telemetry/spec-sponsors @open-telemetry/profiling-maintainers @open-telemetry/profiling-approvers
+opentelemetry/proto/profiles  @open-telemetry/spec-sponsors @open-telemetry/profiling-approvers
+opentelemetry/proto/collector/profiles  @open-telemetry/spec-sponsors @open-telemetry/profiling-approvers
diff --git a/.github/workflows/build-check.yaml b/.github/workflows/build-check.yaml
index d6ca3832b..cd8209695 100644
--- a/.github/workflows/build-check.yaml
+++ b/.github/workflows/build-check.yaml
@@ -6,12 +6,15 @@ on:
   pull_request:
     branches: [ main ]
 
+permissions:
+  contents: read
+
 jobs:
   docker-pull:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout Repo
-        uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+        uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
       - name: Run docker pull
         run: make docker-pull
 
@@ -20,7 +23,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout Repo
-        uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+        uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
       - name: Generate C++
         run: make gen-cpp
 
@@ -29,7 +32,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout Repo
-        uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+        uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
       - name: Generate C#
         run: make gen-csharp
 
@@ -38,7 +41,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout Repo
-        uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+        uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
       - name: Generate GoLang
         run: make gen-go
 
@@ -47,7 +50,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout Repo
-        uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+        uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
       - name: Generate Java
         run: make gen-java
 
@@ -56,7 +59,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout Repo
-        uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+        uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
       - name: Generate ObjC
         run: make gen-objc
 
@@ -65,7 +68,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout Repo
-        uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+        uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
       - name: Generate OpenAPI
         run: make gen-openapi
 
@@ -74,7 +77,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout Repo
-        uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+        uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
       - name: Generate PhP
         run: make gen-php
 
@@ -83,7 +86,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout Repo
-        uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+        uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
       - name: Generate Python
         run: make gen-python
 
@@ -92,7 +95,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout Repo
-        uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+        uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
       - name: Generate Ruby
         run: make gen-ruby
     
@@ -101,7 +104,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout Repo
-        uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+        uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
       - name: Generate Kotlin
         run: make gen-kotlin
 
@@ -110,7 +113,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout Repo
-        uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+        uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
       # breaking-change checks against last published release which is determined
       # using the last published tag
       - name: Get tags
@@ -127,7 +130,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout Repo
-        uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+        uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
 
       - name: run markdown-link-check
         run: make markdown-link-check
@@ -136,7 +139,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout Repo
-        uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+        uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
 
       - name: run markdownlint
         run: make markdownlint
\ No newline at end of file
diff --git a/.github/workflows/codeql.yml b/.github/workflows/codeql.yml
new file mode 100644
index 000000000..a65d1e15e
--- /dev/null
+++ b/.github/workflows/codeql.yml
@@ -0,0 +1,35 @@
+name: CodeQL
+
+on:
+  pull_request:
+    branches:
+      - main
+  push:
+    branches:
+      - main
+  schedule:
+    - cron: "47 8 * * 4"  # weekly at 08:47 UTC on Thursday
+
+permissions:
+  contents: read
+
+jobs:
+  analyze:
+    name: Analyze GitHub Actions
+    permissions:
+      contents: read
+      actions: read  # for github/codeql-action/init to get workflow details
+      security-events: write  # for github/codeql-action/analyze to upload SARIF results
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
+
+      - name: Initialize CodeQL
+        uses: github/codeql-action/init@3c3833e0f8c1c83d449a7478aa59c036a9165498 # v3.29.11
+        with:
+          languages: actions
+
+      - name: Perform CodeQL analysis
+        uses: github/codeql-action/analyze@3c3833e0f8c1c83d449a7478aa59c036a9165498 # v3.29.11
+        with:
+          category: "/language:actions"
diff --git a/.github/workflows/fossa.yml b/.github/workflows/fossa.yml
index 86b1a94e1..f86b5a993 100644
--- a/.github/workflows/fossa.yml
+++ b/.github/workflows/fossa.yml
@@ -12,7 +12,7 @@ jobs:
   fossa:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+      - uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
 
       - uses: fossas/fossa-action@3ebcea1862c6ffbd5cf1b4d0bd6b3fe7bd6f2cac # v1.7.0
         with:
diff --git a/.github/workflows/ossf-scorecard.yml b/.github/workflows/ossf-scorecard.yml
index 990fe2fa5..e1ba6cdc8 100644
--- a/.github/workflows/ossf-scorecard.yml
+++ b/.github/workflows/ossf-scorecard.yml
@@ -19,7 +19,7 @@ jobs:
       # Needed for GitHub OIDC token if publish_results is true
       id-token: write
     steps:
-      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+      - uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
         with:
           persist-credentials: false
 
@@ -42,6 +42,6 @@ jobs:
       # Upload the results to GitHub's code scanning dashboard (optional).
       # Commenting out will disable upload of results to your repo's Code Scanning dashboard
       - name: "Upload to code-scanning"
-        uses: github/codeql-action/upload-sarif@181d5eefc20863364f96762470ba6f862bdef56b # v3.29.2
+        uses: github/codeql-action/upload-sarif@3c3833e0f8c1c83d449a7478aa59c036a9165498 # v3.29.11
         with:
           sarif_file: results.sarif
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 651dc80cd..8c333a8bd 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,10 @@
 
 The full list of changes can be found in the compare view for the respective release at <https://github.com/open-telemetry/opentelemetry-proto/releases>.
 
+### Added
+
+- all: add notes about the attribute values restrictions. [#683](https://github.com/open-telemetry/opentelemetry-proto/pull/683)
+
 ## 1.7.0 - 2025-05-19
 
 ### Added
diff --git a/opentelemetry/proto/metrics/v1/metrics.proto b/opentelemetry/proto/metrics/v1/metrics.proto
index a42e51a60..8915e3c16 100644
--- a/opentelemetry/proto/metrics/v1/metrics.proto
+++ b/opentelemetry/proto/metrics/v1/metrics.proto
@@ -377,6 +377,16 @@ message NumberDataPoint {
   // where this point belongs. The list may be empty (may contain 0 elements).
   // Attribute keys MUST be unique (it is not allowed to have more than one
   // attribute with the same key).
+  //
+  // The attribute values SHOULD NOT contain empty values.
+  // The attribute values SHOULD NOT contain bytes values.
+  // The attribute values SHOULD NOT contain array values different than array of string values, bool values, int values,
+  // double values.
+  // The attribute values SHOULD NOT contain kvlist values.
+  // The behavior of software that receives attributes containing such values can be unpredictable.
+  // These restrictions can change in a minor release.
+  // The restrictions take origin from the OpenTelemetry specification:
+  // https://github.com/open-telemetry/opentelemetry-specification/blob/v1.47.0/specification/common/README.md#attribute.
   repeated opentelemetry.proto.common.v1.KeyValue attributes = 7;
 
   // StartTimeUnixNano is optional but strongly encouraged, see the
@@ -425,6 +435,16 @@ message HistogramDataPoint {
   // where this point belongs. The list may be empty (may contain 0 elements).
   // Attribute keys MUST be unique (it is not allowed to have more than one
   // attribute with the same key).
+  //
+  // The attribute values SHOULD NOT contain empty values.
+  // The attribute values SHOULD NOT contain bytes values.
+  // The attribute values SHOULD NOT contain array values different than array of string values, bool values, int values,
+  // double values.
+  // The attribute values SHOULD NOT contain kvlist values.
+  // The behavior of software that receives attributes containing such values can be unpredictable.
+  // These restrictions can change in a minor release.
+  // The restrictions take origin from the OpenTelemetry specification:
+  // https://github.com/open-telemetry/opentelemetry-specification/blob/v1.47.0/specification/common/README.md#attribute.
   repeated opentelemetry.proto.common.v1.KeyValue attributes = 9;
 
   // StartTimeUnixNano is optional but strongly encouraged, see the
@@ -509,6 +529,16 @@ message ExponentialHistogramDataPoint {
   // where this point belongs. The list may be empty (may contain 0 elements).
   // Attribute keys MUST be unique (it is not allowed to have more than one
   // attribute with the same key).
+  //
+  // The attribute values SHOULD NOT contain empty values.
+  // The attribute values SHOULD NOT contain bytes values.
+  // The attribute values SHOULD NOT contain array values different than array of string values, bool values, int values,
+  // double values.
+  // The attribute values SHOULD NOT contain kvlist values.
+  // The behavior of software that receives attributes containing such values can be unpredictable.
+  // These restrictions can change in a minor release.
+  // The restrictions take origin from the OpenTelemetry specification:
+  // https://github.com/open-telemetry/opentelemetry-specification/blob/v1.47.0/specification/common/README.md#attribute.
   repeated opentelemetry.proto.common.v1.KeyValue attributes = 1;
 
   // StartTimeUnixNano is optional but strongly encouraged, see the
@@ -625,6 +655,16 @@ message SummaryDataPoint {
   // where this point belongs. The list may be empty (may contain 0 elements).
   // Attribute keys MUST be unique (it is not allowed to have more than one
   // attribute with the same key).
+  //
+  // The attribute values SHOULD NOT contain empty values.
+  // The attribute values SHOULD NOT contain bytes values.
+  // The attribute values SHOULD NOT contain array values different than array of string values, bool values, int values,
+  // double values.
+  // The attribute values SHOULD NOT contain kvlist values.
+  // The behavior of software that receives attributes containing such values can be unpredictable.
+  // These restrictions can change in a minor release.
+  // The restrictions take origin from the OpenTelemetry specification:
+  // https://github.com/open-telemetry/opentelemetry-specification/blob/v1.47.0/specification/common/README.md#attribute.
   repeated opentelemetry.proto.common.v1.KeyValue attributes = 7;
 
   // StartTimeUnixNano is optional but strongly encouraged, see the
diff --git a/opentelemetry/proto/profiles/v1development/profiles.proto b/opentelemetry/proto/profiles/v1development/profiles.proto
index 59fd609ff..dc101770d 100644
--- a/opentelemetry/proto/profiles/v1development/profiles.proto
+++ b/opentelemetry/proto/profiles/v1development/profiles.proto
@@ -59,7 +59,7 @@ option go_package = "go.opentelemetry.io/proto/otlp/profiles/v1development";
 // │  ScopeProfiles   │
 // └──────────────────┘
 //   │
-//   │ 1-1
+//   │ 1-n
 //   ▼
 // ┌──────────────────┐
 // │      Profile     │
@@ -67,15 +67,21 @@ option go_package = "go.opentelemetry.io/proto/otlp/profiles/v1development";
 //   │                                n-1
 //   │ 1-n         ┌───────────────────────────────────────┐
 //   ▼             │                                       ▽
-// ┌──────────────────┐   1-n   ┌──────────────┐      ┌──────────┐
-// │      Sample      │ ──────▷ │   KeyValue   │      │   Link   │
-// └──────────────────┘         └──────────────┘      └──────────┘
-//   │                    1-n       △      △
-//   │ 1-n        ┌─────────────────┘      │ 1-n
-//   ▽            │                        │
-// ┌──────────────────┐   n-1   ┌──────────────┐
-// │     Location     │ ──────▷ │   Mapping    │
-// └──────────────────┘         └──────────────┘
+// ┌──────────────────┐   1-n   ┌─────────────────┐   ┌──────────┐
+// │      Sample      │ ──────▷ │ KeyValueAndUnit │   │   Link   │
+// └──────────────────┘         └─────────────────┘   └──────────┘
+//   │                              △      △
+//   │ n-1                          │      │ 1-n
+//   ▽                              │      │
+// ┌──────────────────┐             │      │
+// │      Stack       │             │      │
+// └──────────────────┘             │      │
+//   │                     1-n      │      │
+//   │ 1-n         ┌────────────────┘      │
+//   ▽             │                       │
+// ┌──────────────────┐   n-1   ┌─────────────┐
+// │     Location     │ ──────▷ │   Mapping   │
+// └──────────────────┘         └─────────────┘
 //   │
 //   │ 1-n
 //   ▼
@@ -92,22 +98,23 @@ option go_package = "go.opentelemetry.io/proto/otlp/profiles/v1development";
 
 // ProfilesDictionary represents the profiles data shared across the
 // entire message being sent.
+//
+// Note that all fields in this message MUST have a zero value encoded as the first element.
+// This allows for _index fields pointing into the dictionary to use a 0 pointer value
+// to indicate 'null' / 'not set'. Unless otherwise defined, a 'zero value' message value
+// is one with all default field values, so as to minimize wire encoded size.
 message ProfilesDictionary {
   // Mappings from address ranges to the image/binary/library mapped
   // into that address range referenced by locations via Location.mapping_index.
-  // mapping_table[0] must always be set to a zero value default mapping,
-  // so that _index fields can use 0 to indicate null/unset.
   repeated Mapping mapping_table = 1;
 
-  // Locations referenced by samples via Profile.location_indices.
+  // Locations referenced by samples via Stack.location_indices.
   repeated Location location_table = 2;
 
   // Functions referenced by locations via Line.function_index.
   repeated Function function_table = 3;
 
   // Links referenced by samples via Sample.link_index.
-  // link_table[0] must always be set to a zero value default link,
-  // so that _index fields can use 0 to indicate null/unset.
   repeated Link link_table = 4;
 
   // A common table for strings referenced by various messages.
@@ -115,10 +122,27 @@ message ProfilesDictionary {
   repeated string string_table = 5;
 
   // A common table for attributes referenced by various messages.
-  repeated opentelemetry.proto.common.v1.KeyValue attribute_table = 6;
-
-  // Represents a mapping between Attribute Keys and Units.
-  repeated AttributeUnit attribute_units = 7;
+  // It is a collection of key/value pairs. Note, global attributes
+  // like server name can be set using the resource API. Examples of attributes:
+  //
+  //     "/http/user_agent": "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/71.0.3578.98 Safari/537.36"
+  //     "/http/server_latency": 300
+  //     "abc.com/myattribute": true
+  //     "abc.com/score": 10.239
+  //
+  // The attribute values SHOULD NOT contain empty values.
+  // The attribute values SHOULD NOT contain bytes values.
+  // The attribute values SHOULD NOT contain array values different than array of string values, bool values, int values,
+  // double values.
+  // The attribute values SHOULD NOT contain kvlist values.
+  // The behavior of software that receives attributes containing such values can be unpredictable.
+  // These restrictions can change in a minor release.
+  // The restrictions take origin from the OpenTelemetry specification:
+  // https://github.com/open-telemetry/opentelemetry-specification/blob/v1.47.0/specification/common/README.md#attribute.
+  repeated KeyValueAndUnit attribute_table = 6;
+
+  // Stacks referenced by samples via Sample.stack_index.
+  repeated Stack stack_table = 7;
 }
 
 // ProfilesData represents the profiles data that can be stored in persistent storage,
@@ -139,6 +163,8 @@ message ProfilesData {
   // from non-containerized processes.
   // Other resource groupings are possible as well and clarified via
   // Resource.attributes and semantic conventions.
+  // Tools that visualize profiles should prefer displaying
+  // resources_profiles[0].scope_profiles[0].profiles[0] by default.
   repeated ResourceProfiles resource_profiles = 1;
 
   // One instance of ProfilesDictionary
@@ -182,10 +208,6 @@ message ScopeProfiles {
   // https://opentelemetry.io/docs/specs/otel/schemas/#schema-url
   // This schema_url applies to all profiles in the "profiles" field.
   string schema_url = 3;
-
-  // The preferred type and unit of Samples in at least one Profile.
-  // See Profile.sample_type for possible values.
-  ValueType default_sample_type = 4;
 }
 
 // Profile is a common stacktrace profile format.
@@ -201,18 +223,19 @@ message ScopeProfiles {
 //   information present to determine the original sampled values.
 //
 // - The profile is represented as a set of samples, where each sample
-//   references a sequence of locations, and where each location belongs
+//   references a stack trace which is a list of locations, each belonging
 //   to a mapping.
-// - There is a N->1 relationship from sample.location_id entries to
-//   locations. For every sample.location_id entry there must be a
+// - There is a N->1 relationship from Stack.location_indices entries to
+//   locations. For every Stack.location_indices entry there must be a
 //   unique Location with that index.
 // - There is an optional N->1 relationship from locations to
 //   mappings. For every nonzero Location.mapping_id there must be a
 //   unique Mapping with that index.
 
-// Represents a complete profile, including sample types, samples,
-// mappings to binaries, locations, functions, string table, and additional metadata.
-// It modifies and annotates pprof Profile with OpenTelemetry specific fields.
+// Represents a complete profile, including sample types, samples, mappings to
+// binaries, stacks, locations, functions, string table, and additional
+// metadata. It modifies and annotates pprof Profile with OpenTelemetry
+// specific fields.
 //
 // Note that whilst fields in this message retain the name and field id from pprof in most cases
 // for ease of understanding data migration, it is not intended that pprof:Profile and
@@ -227,27 +250,24 @@ message Profile {
   // The set of samples recorded in this profile.
   repeated Sample sample = 2;
 
-  // References to locations in ProfilesDictionary.location_table.
-  repeated int32 location_indices = 3;
-
-  // The following fields 4-14 are informational, do not affect
+  // The following fields 3-12 are informational, do not affect
   // interpretation of results.
 
   // Time of collection (UTC) represented as nanoseconds past the epoch.
-  int64 time_nanos = 4;
+  fixed64 time_unix_nano = 3;
   // Duration of the profile, if a duration makes sense.
-  int64 duration_nanos = 5;
+  uint64 duration_nano = 4;
   // The kind of events between sampled occurrences.
   // e.g [ "cpu","cycles" ] or [ "heap","bytes" ]
-  ValueType period_type = 6;
+  ValueType period_type = 5;
   // The number of events between sampled occurrences.
-  int64 period = 7;
+  int64 period = 6;
   // Free-form text associated with the profile. The text is displayed as is
   // to the user by the tools that read profiles (e.g. by pprof). This field
   // should not be used to store any machine-readable information, it is only
   // for human-friendly content. The profile must stay functional if this field
   // is cleaned.
-  repeated int32 comment_strindices = 8; // Indices into ProfilesDictionary.string_table.
+  repeated int32 comment_strindices = 7; // Indices into ProfilesDictionary.string_table.
 
   // A globally unique identifier for a profile. The ID is a 16-byte array. An ID with
   // all zeroes is considered invalid. It may be used for deduplication and signal
@@ -255,15 +275,15 @@ message Profile {
   // in this field as not equal, even if they represented the same object at an earlier
   // time.
   // This field is optional; an ID may be assigned to an ID-less profile in a later step.
-  bytes profile_id = 9;
+  bytes profile_id = 8;
 
   // dropped_attributes_count is the number of attributes that were discarded. Attributes
   // can be discarded because their keys are too long or because there are too many
   // attributes. If this value is 0, then no attributes were dropped.
-  uint32 dropped_attributes_count = 10;
+  uint32 dropped_attributes_count = 9;
 
   // Specifies format of the original payload. Common values are defined in semantic conventions. [required if original_payload is present]
-  string original_payload_format = 11;
+  string original_payload_format = 10;
 
   // Original payload can be stored in this field. This can be useful for users who want to get the original payload.
   // Formats such as JFR are highly extensible and can contain more information than what is defined in this spec.
@@ -271,30 +291,10 @@ message Profile {
   // If the original payload is in pprof format, it SHOULD not be included in this field.
   // The field is optional, however if it is present then equivalent converted data should be populated in other fields
   // of this message as far as is practicable.
-  bytes original_payload = 12;
+  bytes original_payload = 11;
 
   // References to attributes in attribute_table. [optional]
-  // It is a collection of key/value pairs. Note, global attributes
-  // like server name can be set using the resource API. Examples of attributes:
-  //
-  //     "/http/user_agent": "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/71.0.3578.98 Safari/537.36"
-  //     "/http/server_latency": 300
-  //     "abc.com/myattribute": true
-  //     "abc.com/score": 10.239
-  //
-  // The OpenTelemetry API specification further restricts the allowed value types:
-  // https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/common/README.md#attribute
-  // Attribute keys MUST be unique (it is not allowed to have more than one
-  // attribute with the same key).
-  repeated int32 attribute_indices = 13;
-}
-
-// Represents a mapping between Attribute Keys and Units.
-message AttributeUnit {
-  // Index into string table.
-  int32 attribute_key_strindex = 1;
-  // Index into string table.
-  int32 unit_strindex = 2;
+  repeated int32 attribute_indices = 12;
 }
 
 // A pointer from a profile Sample to a trace Span.
@@ -407,23 +407,20 @@ message ValueType {
 //    values: [2, 2, 3, 3]
 //    timestamps_unix_nano: [1, 2, 3, 4]
 message Sample {
-  // locations_start_index along with locations_length refers to to a slice of locations in Profile.location_indices.
-  int32 locations_start_index = 1;
-  // locations_length along with locations_start_index refers to a slice of locations in Profile.location_indices.
-  // Supersedes location_index.
-  int32 locations_length = 2;
+  // Reference to stack in ProfilesDictionary.stack_table.
+  int32 stack_index = 1;
   // The type and unit of each value is defined by Profile.sample_type.
-  repeated int64 values = 3;
+  repeated int64 values = 2;
   // References to attributes in ProfilesDictionary.attribute_table. [optional]
-  repeated int32 attribute_indices = 4;
+  repeated int32 attribute_indices = 3;
 
   // Reference to link in ProfilesDictionary.link_table. [optional]
   // It can be unset / set to 0 if no link exists, as link_table[0] is always a 'null' default value.
-  int32 link_index = 5;
+  int32 link_index = 4;
 
   // Timestamps associated with Sample represented in nanoseconds. These
   // timestamps should fall within the Profile's time range.
-  repeated uint64 timestamps_unix_nano = 6;
+  repeated fixed64 timestamps_unix_nano = 5;
 }
 
 // Describes the mapping of a binary in memory, including its address range,
@@ -441,11 +438,13 @@ message Mapping {
   int32 filename_strindex = 4;  // Index into ProfilesDictionary.string_table.
   // References to attributes in ProfilesDictionary.attribute_table. [optional]
   repeated int32 attribute_indices = 5;
-  // The following fields indicate the resolution of symbolic info.
-  bool has_functions = 6;
-  bool has_filenames = 7;
-  bool has_line_numbers = 8;
-  bool has_inline_frames = 9;
+}
+
+// A Stack represents a stack trace as a list of locations.
+message Stack {
+  // References to locations in ProfilesDictionary.location_table.
+  // The first location is the leaf frame.
+  repeated int32 location_indices = 1;
 }
 
 // Describes function and line table debug information.
@@ -468,15 +467,8 @@ message Location {
   //    line[0].function_name == "memcpy"
   //    line[1].function_name == "printf"
   repeated Line line = 3;
-  // Provides an indication that multiple symbols map to this location's
-  // address, for example due to identical code folding by the linker. In that
-  // case the line information above represents one of the multiple
-  // symbols. This field must be recomputed when the symbolization state of the
-  // profile changes.
-  bool is_folded = 4;
-
   // References to attributes in ProfilesDictionary.attribute_table. [optional]
-  repeated int32 attribute_indices = 5;
+  repeated int32 attribute_indices = 4;
 }
 
 // Details a specific line in a source code, linked to a function.
@@ -502,3 +494,12 @@ message Function {
   // Line number in source file. 0 means unset.
   int64 start_line = 4;
 }
+
+// A custom 'dictionary native' style of encoding attributes which is more convenient
+// for profiles than opentelemetry.proto.common.v1.KeyValue
+// Specifically, uses the string table for keys and allows optional unit information.
+message KeyValueAndUnit {
+  int32 key_strindex  = 1;
+  opentelemetry.proto.common.v1.AnyValue value = 2;
+  int32 unit_strindex = 3; // zero indicates implicit (by semconv) or non-defined unit.
+}
diff --git a/opentelemetry/proto/resource/v1/resource.proto b/opentelemetry/proto/resource/v1/resource.proto
index 05d445684..8affbe332 100644
--- a/opentelemetry/proto/resource/v1/resource.proto
+++ b/opentelemetry/proto/resource/v1/resource.proto
@@ -29,6 +29,16 @@ message Resource {
   // Set of attributes that describe the resource.
   // Attribute keys MUST be unique (it is not allowed to have more than one
   // attribute with the same key).
+  //
+  // The attribute values SHOULD NOT contain empty values.
+  // The attribute values SHOULD NOT contain bytes values.
+  // The attribute values SHOULD NOT contain array values different than array of string values, bool values, int values,
+  // double values.
+  // The attribute values SHOULD NOT contain kvlist values.
+  // The behavior of software that receives attributes containing such values can be unpredictable.
+  // These restrictions can change in a minor release.
+  // The restrictions take origin from the OpenTelemetry specification:
+  // https://github.com/open-telemetry/opentelemetry-specification/blob/v1.47.0/specification/common/README.md#attribute.
   repeated opentelemetry.proto.common.v1.KeyValue attributes = 1;
 
   // dropped_attributes_count is the number of dropped attributes. If the value is 0, then
diff --git a/opentelemetry/proto/trace/v1/trace.proto b/opentelemetry/proto/trace/v1/trace.proto
index 24442853e..fec6f9e3a 100644
--- a/opentelemetry/proto/trace/v1/trace.proto
+++ b/opentelemetry/proto/trace/v1/trace.proto
@@ -206,10 +206,18 @@ message Span {
   //     "example.com/myattribute": true
   //     "example.com/score": 10.239
   //
-  // The OpenTelemetry API specification further restricts the allowed value types:
-  // https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/common/README.md#attribute
   // Attribute keys MUST be unique (it is not allowed to have more than one
   // attribute with the same key).
+  //
+  // The attribute values SHOULD NOT contain empty values.
+  // The attribute values SHOULD NOT contain bytes values.
+  // The attribute values SHOULD NOT contain array values different than array of string values, bool values, int values,
+  // double values.
+  // The attribute values SHOULD NOT contain kvlist values.
+  // The behavior of software that receives attributes containing such values can be unpredictable.
+  // These restrictions can change in a minor release.
+  // The restrictions take origin from the OpenTelemetry specification:
+  // https://github.com/open-telemetry/opentelemetry-specification/blob/v1.47.0/specification/common/README.md#attribute.
   repeated opentelemetry.proto.common.v1.KeyValue attributes = 9;
 
   // dropped_attributes_count is the number of attributes that were discarded. Attributes
@@ -230,6 +238,16 @@ message Span {
     // attributes is a collection of attribute key/value pairs on the event.
     // Attribute keys MUST be unique (it is not allowed to have more than one
     // attribute with the same key).
+    //
+    // The attribute values SHOULD NOT contain empty values.
+    // The attribute values SHOULD NOT contain bytes values.
+    // The attribute values SHOULD NOT contain array values different than array of string values, bool values, int values,
+    // double values.
+    // The attribute values SHOULD NOT contain kvlist values.
+    // The behavior of software that receives attributes containing such values can be unpredictable.
+    // These restrictions can change in a minor release.
+    // The restrictions take origin from the OpenTelemetry specification:
+    // https://github.com/open-telemetry/opentelemetry-specification/blob/v1.47.0/specification/common/README.md#attribute.
     repeated opentelemetry.proto.common.v1.KeyValue attributes = 3;
 
     // dropped_attributes_count is the number of dropped attributes. If the value is 0,
@@ -262,6 +280,16 @@ message Span {
     // attributes is a collection of attribute key/value pairs on the link.
     // Attribute keys MUST be unique (it is not allowed to have more than one
     // attribute with the same key).
+    //
+    // The attribute values SHOULD NOT contain empty values.
+    // The attribute values SHOULD NOT contain bytes values.
+    // The attribute values SHOULD NOT contain array values different than array of string values, bool values, int values,
+    // double values.
+    // The attribute values SHOULD NOT contain kvlist values.
+    // The behavior of software that receives attributes containing such values can be unpredictable.
+    // These restrictions can change in a minor release.
+    // The restrictions take origin from the OpenTelemetry specification:
+    // https://github.com/open-telemetry/opentelemetry-specification/blob/v1.47.0/specification/common/README.md#attribute.
     repeated opentelemetry.proto.common.v1.KeyValue attributes = 4;
 
     // dropped_attributes_count is the number of dropped attributes. If the value is 0,