diff --git a/core/java/com/android/internal/inputmethod/InputMethodUtils.java b/core/java/com/android/internal/inputmethod/InputMethodUtils.java
index 7f289d0555bc4..1e5b5c80f31b4 100644
--- a/core/java/com/android/internal/inputmethod/InputMethodUtils.java
+++ b/core/java/com/android/internal/inputmethod/InputMethodUtils.java
@@ -67,7 +67,6 @@ public class InputMethodUtils {
     private static final String NOT_A_SUBTYPE_ID_STR = String.valueOf(NOT_A_SUBTYPE_ID);
     private static final String TAG_ENABLED_WHEN_DEFAULT_IS_NOT_ASCII_CAPABLE =
             "EnabledWhenDefaultIsNotAsciiCapable";
-    private static final String TAG_ASCII_CAPABLE = "AsciiCapable";
 
     // The string for enabled input method is saved as follows:
     // example: ("ime0;subtype0;subtype1;subtype2:ime1:ime2;subtype0")
@@ -539,7 +538,7 @@ public class InputMethodUtils {
             final int numApplicationSubtypes = applicableSubtypes.size();
             for (int i = 0; i < numApplicationSubtypes; ++i) {
                 final InputMethodSubtype subtype = applicableSubtypes.get(i);
-                if (subtype.containsExtraValueKey(TAG_ASCII_CAPABLE)) {
+                if (subtype.isAsciiCapable()) {
                     hasAsciiCapableKeyboard = true;
                     break;
                 }
diff --git a/core/res/res/values/attrs.xml b/core/res/res/values/attrs.xml
index 21c10ce89c1a7..158d4e57934f2 100644
--- a/core/res/res/values/attrs.xml
+++ b/core/res/res/values/attrs.xml
@@ -3419,10 +3419,16 @@
              constructor or 0. Arrays.hashCode(new Object[] {locale, mode, extraValue,
              isAuxiliary, overridesImplicitlyEnabledSubtype}) will be used instead. -->
         <attr name="subtypeId" format="integer"/>
-        <!-- Set to true if this subtype is ASCII capable. If the subtype is ASCII
+        <!-- Set to {@code true} if this subtype is ASCII capable. If the subtype is ASCII
              capable, it should guarantee that the user can input ASCII characters with
              this subtype. This is important because many password fields only allow
-             ASCII-characters. -->
+             ASCII-characters.
+
+             <p>Note: In order to avoid some known system issues on
+             {@link android.os.Build.VERSION_CODES#P} and prior OSes, you may want to include
+             {@code "AsciiCapable"} in
+             {@link android.R.styleable#InputMethod_Subtype_imeSubtypeExtraValue} when you specify
+             {@code true} to this attribute.-->
         <attr name="isAsciiCapable" format="boolean" />
         <!-- The BCP-47 Language Tag of the subtype.  This replaces
         {@link android.R.styleable#InputMethod_Subtype_imeSubtypeLocale}.  -->
diff --git a/core/tests/coretests/src/com/android/internal/inputmethod/InputMethodUtilsTest.java b/core/tests/coretests/src/com/android/internal/inputmethod/InputMethodUtilsTest.java
index 863cf05ec95fc..a49e203532afd 100644
--- a/core/tests/coretests/src/com/android/internal/inputmethod/InputMethodUtilsTest.java
+++ b/core/tests/coretests/src/com/android/internal/inputmethod/InputMethodUtilsTest.java
@@ -87,7 +87,6 @@ public class InputMethodUtilsTest {
     private static final String SUBTYPE_MODE_HANDWRITING = "handwriting";
     private static final String SUBTYPE_MODE_ANY = null;
     private static final String EXTRA_VALUE_PAIR_SEPARATOR = ",";
-    private static final String EXTRA_VALUE_ASCII_CAPABLE = "AsciiCapable";
     private static final String EXTRA_VALUE_ENABLED_WHEN_DEFAULT_IS_NOT_ASCII_CAPABLE =
             "EnabledWhenDefaultIsNotAsciiCapable";
 
@@ -910,13 +909,6 @@ public class InputMethodUtilsTest {
             subtypeExtraValue.append(EXTRA_VALUE_ENABLED_WHEN_DEFAULT_IS_NOT_ASCII_CAPABLE);
         }
 
-        // TODO: Remove following code. InputMethodSubtype#isAsciiCapable() has been publicly
-        // available since API level 19 (KitKat). We no longer need to rely on extra value.
-        if (isAsciiCapable) {
-            subtypeExtraValue.append(EXTRA_VALUE_PAIR_SEPARATOR);
-            subtypeExtraValue.append(EXTRA_VALUE_ASCII_CAPABLE);
-        }
-
         return new InputMethodSubtypeBuilder()
                 .setSubtypeNameResId(0)
                 .setSubtypeIconResId(0)