diff --git a/src/main/java/com/google/devtools/build/docgen/ApiExporter.java b/src/main/java/com/google/devtools/build/docgen/ApiExporter.java
index aeed62b..46a4695 100644
--- a/src/main/java/com/google/devtools/build/docgen/ApiExporter.java
+++ b/src/main/java/com/google/devtools/build/docgen/ApiExporter.java
@@ -14,6 +14,7 @@
 package com.google.devtools.build.docgen;
 
 import com.google.common.collect.ImmutableList;
+import com.google.devtools.build.docgen.builtin.BuiltinProtos.ApiContext;
 import com.google.devtools.build.docgen.builtin.BuiltinProtos.Builtins;
 import com.google.devtools.build.docgen.builtin.BuiltinProtos.Callable;
 import com.google.devtools.build.docgen.builtin.BuiltinProtos.Param;
@@ -47,48 +48,88 @@
       throws BuildEncyclopediaDocException {
 
     for (Entry<String, SkylarkModuleDoc> modEntry : types.entrySet()) {
-        SkylarkModuleDoc mod = modEntry.getValue();
+      SkylarkModuleDoc mod = modEntry.getValue();
 
-        Type.Builder type = Type.newBuilder();
-        type.setName(mod.getName());
-        type.setDoc(mod.getDocumentation());
-        for (SkylarkMethodDoc meth : mod.getJavaMethods()) {
+      Type.Builder type = Type.newBuilder();
+      type.setName(mod.getName());
+      type.setDoc(mod.getDocumentation());
+      for (SkylarkMethodDoc meth : mod.getJavaMethods()) {
         // Constructors are exported as global symbols.
         if (!(meth instanceof SkylarkConstructorMethodDoc)) {
-          type.addField(collectMethodInfo(meth));
+          Value.Builder value = collectMethodInfo(meth);
+          // Methods from the native package are available as top level functions in BUILD files.
+          if (mod.getName().equals("native")) {
+            value.setApiContext(ApiContext.BUILD);
+            builtins.addGlobal(value);
+
+            value.setApiContext(ApiContext.BZL);
+            type.addField(value);
+          } else {
+            value.setApiContext(ApiContext.ALL);
+            type.addField(value);
           }
         }
-        // Add native rules to the native type.
-        if (mod.getName().equals("native")) {
+      }
+      // Native rules are available in BZL file as methods of the native package.
+      if (mod.getName().equals("native")) {
         for (RuleDocumentation rule : nativeRules) {
-          type.addField(collectRuleInfo(rule));
-          }
+          Value.Builder field = collectRuleInfo(rule);
+          field.setApiContext(ApiContext.BZL);
+          type.addField(field);
         }
-        builtins.addType(type);
+      }
+      builtins.addType(type);
     }
   }
 
-  private static void appendGlobals(Builtins.Builder builtins, Map<String, Object> globals) {
-    for (Entry<String, Object> entry : globals.entrySet()) {
+  // Globals are available for both BUILD and BZL files.
+  private static void appendGlobals(Builtins.Builder builtins, Map<String, Object> globalMethods) {
+    for (Entry<String, Object> entry : globalMethods.entrySet()) {
       Object obj = entry.getValue();
+      Value.Builder value = Value.newBuilder();
+      if (obj instanceof BaseFunction) {
+        value = collectFunctionInfo((BaseFunction) obj);
+      } else {
+        value.setName(entry.getKey());
+      }
+      value.setApiContext(ApiContext.ALL);
+      builtins.addGlobal(value);
+    }
+  }
+
+  private static void appendBzlGlobals(
+      Builtins.Builder builtins, Map<String, Object> starlarkGlobals) {
+    for (Entry<String, Object> entry : starlarkGlobals.entrySet()) {
+      Object obj = entry.getValue();
+      Value.Builder value = Value.newBuilder();
 
       if (obj instanceof BaseFunction) {
-        builtins.addGlobal(collectFunctionInfo((BaseFunction) obj));
+        value = collectFunctionInfo((BaseFunction) obj);
       } else {
-        Value.Builder value = Value.newBuilder();
-        value.setName(entry.getKey());
-
         SkylarkModule typeModule = SkylarkInterfaceUtils.getSkylarkModule(obj.getClass());
         if (typeModule != null) {
           if (FuncallExpression.hasSelfCallMethod(obj.getClass())) {
-            builtins.addGlobal(collectFunctionInfo(FuncallExpression.getSelfCallMethod(obj)));
-            continue;
+            value = collectFunctionInfo(FuncallExpression.getSelfCallMethod(obj));
+          } else {
+            value.setName(entry.getKey());
+            value.setType(entry.getKey());
+            value.setDoc(typeModule.doc());
           }
-          value.setType(entry.getKey());
-          value.setDoc(typeModule.doc());
         }
-        builtins.addGlobal(value);
       }
+      value.setApiContext(ApiContext.BZL);
+      builtins.addGlobal(value);
+    }
+  }
+
+  // Native rules are available as top level functions in BUILD files.
+  private static void appendNativeRules(
+      Builtins.Builder builtins, List<RuleDocumentation> nativeRules)
+      throws BuildEncyclopediaDocException {
+    for (RuleDocumentation rule : nativeRules) {
+      Value.Builder global = collectRuleInfo(rule);
+      global.setApiContext(ApiContext.BUILD);
+      builtins.addGlobal(global);
     }
   }
 
@@ -191,7 +232,9 @@
       Builtins.Builder builtins = Builtins.newBuilder();
 
       appendTypes(builtins, symbols.getTypes(), symbols.getNativeRules());
-      appendGlobals(builtins, symbols.getGlobalSymbols());
+      appendGlobals(builtins, symbols.getGlobals());
+      appendBzlGlobals(builtins, symbols.getBzlGlobals());
+      appendNativeRules(builtins, symbols.getNativeRules());
       writeBuiltins(options.outputFile, builtins);
 
     } catch (Throwable e) {
@@ -200,4 +243,3 @@
     }
   }
 }
-
diff --git a/src/main/java/com/google/devtools/build/docgen/SymbolFamilies.java b/src/main/java/com/google/devtools/build/docgen/SymbolFamilies.java
index 3c08a42..d51e058 100644
--- a/src/main/java/com/google/devtools/build/docgen/SymbolFamilies.java
+++ b/src/main/java/com/google/devtools/build/docgen/SymbolFamilies.java
@@ -66,9 +66,12 @@
  */
 public class SymbolFamilies {
   private final ImmutableList<RuleDocumentation> nativeRules;
-  private final ImmutableMap<String, Object> globalSymbols;
   private final ImmutableMap<String, SkylarkModuleDoc> types;
 
+  // Mappings between Starlark names and Starlark entities generated from the fakebuildapi.
+  private final ImmutableMap<String, Object> globals;
+  private final ImmutableMap<String, Object> bzlGlobals;
+
   public SymbolFamilies(
       String productName, String provider, List<String> inputDirs, String blackList)
       throws NoSuchMethodException, ClassPathException, InvocationTargetException,
@@ -76,7 +79,8 @@
           IOException {
     this.nativeRules =
         ImmutableList.copyOf(collectNativeRules(productName, provider, inputDirs, blackList));
-    this.globalSymbols = ImmutableMap.copyOf(collectGlobalSymbols());
+    this.globals = ImmutableMap.copyOf(collectGlobals());
+    this.bzlGlobals = ImmutableMap.copyOf(collectBzlGlobals());
     this.types = ImmutableMap.copyOf(collectTypes());
   }
 
@@ -88,11 +92,19 @@
   }
 
   /*
-   * Returns a mapping between Starlark module names and Starkark entities generated from the
-   * fakebuildapi.
+   * Returns a mapping between Starlark names and Starkark entities that are available both in BZL
+   * and BUILD files.
    */
-  public Map<String, Object> getGlobalSymbols() {
-    return globalSymbols;
+  public Map<String, Object> getGlobals() {
+    return globals;
+  }
+
+  /*
+   * Returns a mapping between Starlark names and Starkark entities that are available only in BZL
+   * files.
+   */
+  public Map<String, Object> getBzlGlobals() {
+    return bzlGlobals;
   }
 
   // Returns a mapping between type names and module/type documentation.
@@ -100,10 +112,18 @@
     return types;
   }
 
+  /*
+   * Collects a mapping between type names and module/type documentation that are available both
+   * in BZL and BUILD files.
+   */
   private Map<String, SkylarkModuleDoc> collectTypes() throws ClassPathException {
     return SkylarkDocumentationCollector.collectModules();
   }
 
+  /*
+   * Collects a list of native rules that are available in BUILD files as top level functions
+   * and in BZL files as methods of the native package.
+   */
   private List<RuleDocumentation> collectNativeRules(
       String productName, String provider, List<String> inputDirs, String blackList)
       throws NoSuchMethodException, InvocationTargetException, IllegalAccessException,
@@ -114,7 +134,21 @@
     return processor.getNativeRules();
   }
 
-  private Map<String, Object> collectGlobalSymbols() {
+  /*
+   * Collects a mapping between names and Starlark entities that are available both in BZL and
+   * BUILD files.
+   */
+  private Map<String, Object> collectGlobals() {
+    ImmutableMap.Builder<String, Object> envBuilder = ImmutableMap.builder();
+    MethodLibrary.addBindingsToBuilder(envBuilder);
+    Runtime.addConstantsToBuilder(envBuilder);
+    return envBuilder.build();
+  }
+
+  /*
+   * Collects a mapping between names and Starlark entities that are available only in BZL files
+   */
+  private Map<String, Object> collectBzlGlobals() {
     ImmutableMap.Builder<String, Object> envBuilder = ImmutableMap.builder();
     TopLevelBootstrap topLevelBootstrap =
         new TopLevelBootstrap(
@@ -145,8 +179,6 @@
     RepositoryBootstrap repositoryBootstrap = new RepositoryBootstrap(new FakeRepositoryModule());
     TestingBootstrap testingBootstrap = new TestingBootstrap(new FakeTestingModule());
 
-    Runtime.addConstantsToBuilder(envBuilder);
-    MethodLibrary.addBindingsToBuilder(envBuilder);
     topLevelBootstrap.addBindingsToBuilder(envBuilder);
     androidBootstrap.addBindingsToBuilder(envBuilder);
     appleBootstrap.addBindingsToBuilder(envBuilder);
diff --git a/src/main/protobuf/builtin.proto b/src/main/protobuf/builtin.proto
index 72df5a1..9ca7f54 100644
--- a/src/main/protobuf/builtin.proto
+++ b/src/main/protobuf/builtin.proto
@@ -50,6 +50,15 @@
   string doc = 3;
 }
 
+// ApiContext specifies the context(s) in which a symbol is available. For
+// example, a symbol may be available as a builtin only in .bzl files, but
+// not in BUILD files.
+enum ApiContext {
+  ALL = 0;
+  BZL = 1;
+  BUILD = 2;
+}
+
 // Generic representation for a Skylark object. If the object is callable
 // (can act as a function), then callable will be set.
 message Value {
@@ -63,6 +72,9 @@
 
   // Value documentation.
   string doc = 4;
+
+  // The context(s) in which the symbol is recognized.
+  ApiContext api_context = 5;
 }
 
 message Callable {