Modify the documentation of 'Routing'

Bug: 121047189
Test: Treehugger
Change-Id: If2c22916062f7f0dbaa0b98185660f3d33bc254a
diff --git a/current.txt b/current.txt
index f82f741..dca8829 100644
--- a/current.txt
+++ b/current.txt
@@ -429,7 +429,7 @@
 e9d0f11a52715f5a29d89e2d8e2e21db1e16a43174af6b9d51a62d705cda1455 android.hardware.radio@1.3::IRadioIndication
 d233f0da44f55fdef0a95db5229231412787bb67695cd1ea197ce89a3c2908b9 android.hardware.radio@1.3::IRadioResponse
 750a363c8cec70baa1aac19e275c15233c5898e93c6bb5155fa2ca7f365490dc android.hardware.radio@1.3::types
-21e6ce53f1759f6a213ca05bac3c0325ed911f74764d1c1f6fa5ed8068ade65b android.hardware.radio@1.4::IRadio
+4ac73ec1e4cfa535209e5e22547f08beb20ef812b4a29d0824780f52cbe2324d android.hardware.radio@1.4::IRadio
 33d9e6895cca98aa56296bb01720d18b8acd0e4de4960beb712e63ad147438a5 android.hardware.radio@1.4::IRadioIndication
 0cc0dd87c634aad36d7df22b2832839ef7ded71909dbcde11cfdd69dc0dc52b8 android.hardware.radio@1.4::IRadioResponse
 29d34232cc3974626b08759e039fe788bded7695cdeb098458e3e11e4c7d3603 android.hardware.radio@1.4::types
diff --git a/radio/1.4/IRadio.hal b/radio/1.4/IRadio.hal
index f7ae39f..046f074 100644
--- a/radio/1.4/IRadio.hal
+++ b/radio/1.4/IRadio.hal
@@ -115,11 +115,13 @@
      * PUK/PIN state of the subscription and the service state of the radio.
      *
      * Some countries or carriers require some emergency numbers that must be handled with normal
-     * call routing or emergency routing. If the 'routing' field is specified as
-     * @1.4::EmergencyNumberRouting#NORMAL, the implementation must use normal call routing to
-     * handle the call; if it is specified as @1.4::EmergencyNumberRouting#EMERGENCY, the
-     * implementation must use emergency routing to handle the call; if it is
-     * @1.4::EmergencyNumberRouting#UNKNOWN, Android does not know how to handle the call.
+     * call routing if possible or emergency routing. 1) if the 'routing' field is specified as
+     * @1.4::EmergencyNumberRouting#NORMAL, the implementation must try the full radio service to
+     * use normal call routing to handle the call; if service cannot support normal routing, the
+     * implementation must use emergency routing to handle the call. 2) if 'routing' is specified
+     * as @1.4::EmergencyNumberRouting#EMERGENCY, the implementation must use emergency routing to
+     * handle the call. 3) if 'routing' is specified as @1.4::EmergencyNumberRouting#UNKNOWN,
+     * Android does not know how to handle the call.
      *
      * If the dialed emergency number does not have a specified emergency service category, the
      * 'categories' field is set to @1.4::EmergencyServiceCategory#UNSPECIFIED; if the dialed