diff --git a/sdk/Android.bp b/sdk/Android.bp
index 368c03a..5ba2d9d 100644
--- a/sdk/Android.bp
+++ b/sdk/Android.bp
@@ -15,6 +15,7 @@
     ],
     srcs: [
         "bp.go",
+        "build_release.go",
         "exports.go",
         "sdk.go",
         "update.go",
@@ -22,6 +23,7 @@
     testSrcs: [
         "bootclasspath_fragment_sdk_test.go",
         "bp_test.go",
+        "build_release_test.go",
         "cc_sdk_test.go",
         "compat_config_sdk_test.go",
         "exports_test.go",
diff --git a/sdk/build_release.go b/sdk/build_release.go
new file mode 100644
index 0000000..f2379ae
--- /dev/null
+++ b/sdk/build_release.go
@@ -0,0 +1,160 @@
+// Copyright (C) 2021 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package sdk
+
+import (
+	"fmt"
+	"strings"
+)
+
+// Supports customizing sdk snapshot output based on target build release.
+
+// buildRelease represents the version of a build system used to create a specific release.
+//
+// The name of the release, is the same as the code for the dessert release, e.g. S, T, etc.
+type buildRelease struct {
+	// The name of the release, e.g. S, T, etc.
+	name string
+
+	// The index of this structure within the buildReleases list.
+	ordinal int
+}
+
+// String returns the name of the build release.
+func (s *buildRelease) String() string {
+	return s.name
+}
+
+// buildReleaseSet represents a set of buildRelease objects.
+type buildReleaseSet struct {
+	// Set of *buildRelease represented as a map from *buildRelease to struct{}.
+	contents map[*buildRelease]struct{}
+}
+
+// addItem adds a build release to the set.
+func (s *buildReleaseSet) addItem(release *buildRelease) {
+	s.contents[release] = struct{}{}
+}
+
+// addRange adds all the build releases from start (inclusive) to end (inclusive).
+func (s *buildReleaseSet) addRange(start *buildRelease, end *buildRelease) {
+	for i := start.ordinal; i <= end.ordinal; i += 1 {
+		s.addItem(buildReleases[i])
+	}
+}
+
+// contains returns true if the set contains the specified build release.
+func (s *buildReleaseSet) contains(release *buildRelease) bool {
+	_, ok := s.contents[release]
+	return ok
+}
+
+// String returns a string representation of the set, sorted from earliest to latest release.
+func (s *buildReleaseSet) String() string {
+	list := []string{}
+	for _, release := range buildReleases {
+		if _, ok := s.contents[release]; ok {
+			list = append(list, release.name)
+		}
+	}
+	return fmt.Sprintf("[%s]", strings.Join(list, ","))
+}
+
+var (
+	// nameToBuildRelease contains a map from name to build release.
+	nameToBuildRelease = map[string]*buildRelease{}
+
+	// buildReleases lists all the available build releases.
+	buildReleases = []*buildRelease{}
+
+	// allBuildReleaseSet is the set of all build releases.
+	allBuildReleaseSet = &buildReleaseSet{contents: map[*buildRelease]struct{}{}}
+
+	// Add the build releases from oldest to newest.
+	buildReleaseS = initBuildRelease("S")
+	buildReleaseT = initBuildRelease("T")
+)
+
+// initBuildRelease creates a new build release with the specified name.
+func initBuildRelease(name string) *buildRelease {
+	ordinal := len(nameToBuildRelease)
+	release := &buildRelease{name: name, ordinal: ordinal}
+	nameToBuildRelease[name] = release
+	buildReleases = append(buildReleases, release)
+	allBuildReleaseSet.addItem(release)
+	return release
+}
+
+// latestBuildRelease returns the latest build release, i.e. the last one added.
+func latestBuildRelease() *buildRelease {
+	return buildReleases[len(buildReleases)-1]
+}
+
+// nameToRelease maps from build release name to the corresponding build release (if it exists) or
+// the error if it does not.
+func nameToRelease(name string) (*buildRelease, error) {
+	if r, ok := nameToBuildRelease[name]; ok {
+		return r, nil
+	}
+
+	return nil, fmt.Errorf("unknown release %q, expected one of %s", name, allBuildReleaseSet)
+}
+
+// parseBuildReleaseSet parses a build release set string specification into a build release set.
+//
+// The specification consists of one of the following:
+// * a single build release name, e.g. S, T, etc.
+// * a closed range (inclusive to inclusive), e.g. S-T
+// * an open range, e.g. T+.
+//
+// This returns the set if the specification was valid or an error.
+func parseBuildReleaseSet(specification string) (*buildReleaseSet, error) {
+	set := &buildReleaseSet{contents: map[*buildRelease]struct{}{}}
+
+	if strings.HasSuffix(specification, "+") {
+		rangeStart := strings.TrimSuffix(specification, "+")
+		start, err := nameToRelease(rangeStart)
+		if err != nil {
+			return nil, err
+		}
+		end := latestBuildRelease()
+		set.addRange(start, end)
+	} else if strings.Contains(specification, "-") {
+		limits := strings.SplitN(specification, "-", 2)
+		start, err := nameToRelease(limits[0])
+		if err != nil {
+			return nil, err
+		}
+
+		end, err := nameToRelease(limits[1])
+		if err != nil {
+			return nil, err
+		}
+
+		if start.ordinal > end.ordinal {
+			return nil, fmt.Errorf("invalid closed range, start release %q is later than end release %q", start.name, end.name)
+		}
+
+		set.addRange(start, end)
+	} else {
+		release, err := nameToRelease(specification)
+		if err != nil {
+			return nil, err
+		}
+		set.addItem(release)
+	}
+
+	return set, nil
+}
diff --git a/sdk/build_release_test.go b/sdk/build_release_test.go
new file mode 100644
index 0000000..fa6591c
--- /dev/null
+++ b/sdk/build_release_test.go
@@ -0,0 +1,100 @@
+// Copyright (C) 2021 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package sdk
+
+import (
+	"fmt"
+	"testing"
+
+	"android/soong/android"
+)
+
+// Tests for build_release.go
+
+var (
+	// Some additional test specific releases that are added after the currently supported ones and
+	// so are treated as being for future releases.
+	buildReleaseFuture1 = initBuildRelease("F1")
+	buildReleaseFuture2 = initBuildRelease("F2")
+)
+
+func TestNameToRelease(t *testing.T) {
+	t.Run("single release", func(t *testing.T) {
+		release, err := nameToRelease("S")
+		android.AssertDeepEquals(t, "errors", nil, err)
+		android.AssertDeepEquals(t, "release", buildReleaseS, release)
+	})
+	t.Run("invalid release", func(t *testing.T) {
+		release, err := nameToRelease("A")
+		android.AssertDeepEquals(t, "release", (*buildRelease)(nil), release)
+		// Uses a wildcard in the error message to allow for additional build releases to be added to
+		// the supported set without breaking this test.
+		android.FailIfNoMatchingErrors(t, `unknown release "A", expected one of \[S,T.*,F1,F2\]`, []error{err})
+	})
+}
+
+func TestParseBuildReleaseSet(t *testing.T) {
+	t.Run("single release", func(t *testing.T) {
+		set, err := parseBuildReleaseSet("S")
+		android.AssertDeepEquals(t, "errors", nil, err)
+		android.AssertStringEquals(t, "set", "[S]", set.String())
+	})
+	t.Run("open range", func(t *testing.T) {
+		set, err := parseBuildReleaseSet("F1+")
+		android.AssertDeepEquals(t, "errors", nil, err)
+		android.AssertStringEquals(t, "set", "[F1,F2]", set.String())
+	})
+	t.Run("closed range", func(t *testing.T) {
+		set, err := parseBuildReleaseSet("S-F1")
+		android.AssertDeepEquals(t, "errors", nil, err)
+		android.AssertStringEquals(t, "set", "[S,T,F1]", set.String())
+	})
+	invalidAReleaseMessage := `unknown release "A", expected one of ` + allBuildReleaseSet.String()
+	t.Run("invalid release", func(t *testing.T) {
+		set, err := parseBuildReleaseSet("A")
+		android.AssertDeepEquals(t, "set", (*buildReleaseSet)(nil), set)
+		android.AssertStringDoesContain(t, "errors", fmt.Sprint(err), invalidAReleaseMessage)
+	})
+	t.Run("invalid release in open range", func(t *testing.T) {
+		set, err := parseBuildReleaseSet("A+")
+		android.AssertDeepEquals(t, "set", (*buildReleaseSet)(nil), set)
+		android.AssertStringDoesContain(t, "errors", fmt.Sprint(err), invalidAReleaseMessage)
+	})
+	t.Run("invalid release in closed range start", func(t *testing.T) {
+		set, err := parseBuildReleaseSet("A-S")
+		android.AssertDeepEquals(t, "set", (*buildReleaseSet)(nil), set)
+		android.AssertStringDoesContain(t, "errors", fmt.Sprint(err), invalidAReleaseMessage)
+	})
+	t.Run("invalid release in closed range end", func(t *testing.T) {
+		set, err := parseBuildReleaseSet("T-A")
+		android.AssertDeepEquals(t, "set", (*buildReleaseSet)(nil), set)
+		android.AssertStringDoesContain(t, "errors", fmt.Sprint(err), invalidAReleaseMessage)
+	})
+	t.Run("invalid closed range reversed", func(t *testing.T) {
+		set, err := parseBuildReleaseSet("F1-S")
+		android.AssertDeepEquals(t, "set", (*buildReleaseSet)(nil), set)
+		android.AssertStringDoesContain(t, "errors", fmt.Sprint(err), `invalid closed range, start release "F1" is later than end release "S"`)
+	})
+}
+
+func TestBuildReleaseSetContains(t *testing.T) {
+	t.Run("contains", func(t *testing.T) {
+		set, _ := parseBuildReleaseSet("F1-F2")
+		android.AssertBoolEquals(t, "set contains F1", true, set.contains(buildReleaseFuture1))
+		android.AssertBoolEquals(t, "set does not contain S", false, set.contains(buildReleaseS))
+		android.AssertBoolEquals(t, "set contains F2", true, set.contains(buildReleaseFuture2))
+		android.AssertBoolEquals(t, "set does not contain T", false, set.contains(buildReleaseT))
+	})
+}