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
+}