diff --git a/xml/System.Reflection.PortableExecutable/Machine.xml b/xml/System.Reflection.PortableExecutable/Machine.xml
index 6cd4a642570..bdf36f50799 100644
--- a/xml/System.Reflection.PortableExecutable/Machine.xml
+++ b/xml/System.Reflection.PortableExecutable/Machine.xml
@@ -18,7 +18,7 @@
     <BaseTypeName>System.Enum</BaseTypeName>
   </Base>
   <Docs>
-    <summary>To be added.</summary>
+    <summary>Specifies the target machine's CPU architecture.</summary>
     <remarks>To be added.</remarks>
   </Docs>
   <Members>
@@ -44,7 +44,7 @@
       </ReturnValue>
       <MemberValue>388</MemberValue>
       <Docs>
-        <summary>To be added.</summary>
+        <summary>Alpha.</summary>
       </Docs>
     </Member>
     <Member MemberName="Alpha64">
@@ -69,7 +69,7 @@
       </ReturnValue>
       <MemberValue>644</MemberValue>
       <Docs>
-        <summary>To be added.</summary>
+        <summary>ALPHA64.</summary>
       </Docs>
     </Member>
     <Member MemberName="AM33">
@@ -94,7 +94,7 @@
       </ReturnValue>
       <MemberValue>467</MemberValue>
       <Docs>
-        <summary>To be added.</summary>
+        <summary>Matsushita AM33.</summary>
       </Docs>
     </Member>
     <Member MemberName="Amd64">
@@ -119,7 +119,7 @@
       </ReturnValue>
       <MemberValue>34404</MemberValue>
       <Docs>
-        <summary>To be added.</summary>
+        <summary>AMD64 (K8).</summary>
       </Docs>
     </Member>
     <Member MemberName="Arm">
@@ -144,7 +144,7 @@
       </ReturnValue>
       <MemberValue>448</MemberValue>
       <Docs>
-        <summary>To be added.</summary>
+        <summary>ARM little endian.</summary>
       </Docs>
     </Member>
     <Member MemberName="Arm64">
@@ -165,7 +165,7 @@
       </ReturnValue>
       <MemberValue>43620</MemberValue>
       <Docs>
-        <summary>To be added.</summary>
+        <summary>ARM64.</summary>
       </Docs>
     </Member>
     <Member MemberName="ArmThumb2">
@@ -190,7 +190,7 @@
       </ReturnValue>
       <MemberValue>452</MemberValue>
       <Docs>
-        <summary>To be added.</summary>
+        <summary>ARM Thumb-2 little endian.</summary>
       </Docs>
     </Member>
     <Member MemberName="Ebc">
@@ -215,7 +215,7 @@
       </ReturnValue>
       <MemberValue>3772</MemberValue>
       <Docs>
-        <summary>To be added.</summary>
+        <summary>EFI Byte Code.</summary>
       </Docs>
     </Member>
     <Member MemberName="I386">
@@ -240,7 +240,7 @@
       </ReturnValue>
       <MemberValue>332</MemberValue>
       <Docs>
-        <summary>To be added.</summary>
+        <summary>Intel 386.</summary>
       </Docs>
     </Member>
     <Member MemberName="IA64">
@@ -265,7 +265,7 @@
       </ReturnValue>
       <MemberValue>512</MemberValue>
       <Docs>
-        <summary>To be added.</summary>
+        <summary>Intel 64.</summary>
       </Docs>
     </Member>
     <Member MemberName="M32R">
@@ -290,7 +290,7 @@
       </ReturnValue>
       <MemberValue>36929</MemberValue>
       <Docs>
-        <summary>To be added.</summary>
+        <summary>M32R little-endian.</summary>
       </Docs>
     </Member>
     <Member MemberName="MIPS16">
@@ -315,7 +315,7 @@
       </ReturnValue>
       <MemberValue>614</MemberValue>
       <Docs>
-        <summary>To be added.</summary>
+        <summary>MIPS.</summary>
       </Docs>
     </Member>
     <Member MemberName="MipsFpu">
@@ -340,7 +340,7 @@
       </ReturnValue>
       <MemberValue>870</MemberValue>
       <Docs>
-        <summary>To be added.</summary>
+        <summary>MIPS with FPU.</summary>
       </Docs>
     </Member>
     <Member MemberName="MipsFpu16">
@@ -365,7 +365,7 @@
       </ReturnValue>
       <MemberValue>1126</MemberValue>
       <Docs>
-        <summary>To be added.</summary>
+        <summary>MIPS16 with FPU.</summary>
       </Docs>
     </Member>
     <Member MemberName="PowerPC">
@@ -390,7 +390,7 @@
       </ReturnValue>
       <MemberValue>496</MemberValue>
       <Docs>
-        <summary>To be added.</summary>
+        <summary>IBM PowerPC little endian.</summary>
       </Docs>
     </Member>
     <Member MemberName="PowerPCFP">
@@ -415,7 +415,7 @@
       </ReturnValue>
       <MemberValue>497</MemberValue>
       <Docs>
-        <summary>To be added.</summary>
+        <summary>PowerPCFP.</summary>
       </Docs>
     </Member>
     <Member MemberName="SH3">
@@ -440,7 +440,7 @@
       </ReturnValue>
       <MemberValue>418</MemberValue>
       <Docs>
-        <summary>To be added.</summary>
+        <summary>Hitachi SH3 little endian.</summary>
       </Docs>
     </Member>
     <Member MemberName="SH3Dsp">
@@ -465,7 +465,7 @@
       </ReturnValue>
       <MemberValue>419</MemberValue>
       <Docs>
-        <summary>To be added.</summary>
+        <summary>Hitachi SH3 DSP.</summary>
       </Docs>
     </Member>
     <Member MemberName="SH3E">
@@ -490,7 +490,7 @@
       </ReturnValue>
       <MemberValue>420</MemberValue>
       <Docs>
-        <summary>To be added.</summary>
+        <summary>Hitachi SH3 little endian.</summary>
       </Docs>
     </Member>
     <Member MemberName="SH4">
@@ -515,7 +515,7 @@
       </ReturnValue>
       <MemberValue>422</MemberValue>
       <Docs>
-        <summary>To be added.</summary>
+        <summary>Hitachi SH4 little endian.</summary>
       </Docs>
     </Member>
     <Member MemberName="SH5">
@@ -540,7 +540,7 @@
       </ReturnValue>
       <MemberValue>424</MemberValue>
       <Docs>
-        <summary>To be added.</summary>
+        <summary>Hitachi SH5.</summary>
       </Docs>
     </Member>
     <Member MemberName="Thumb">
@@ -565,7 +565,7 @@
       </ReturnValue>
       <MemberValue>450</MemberValue>
       <Docs>
-        <summary>To be added.</summary>
+        <summary>Thumb.</summary>
       </Docs>
     </Member>
     <Member MemberName="Tricore">
@@ -590,7 +590,7 @@
       </ReturnValue>
       <MemberValue>1312</MemberValue>
       <Docs>
-        <summary>To be added.</summary>
+        <summary>Infineon.</summary>
       </Docs>
     </Member>
     <Member MemberName="Unknown">
@@ -615,7 +615,7 @@
       </ReturnValue>
       <MemberValue>0</MemberValue>
       <Docs>
-        <summary>To be added.</summary>
+        <summary>The target CPU is unknown or not specified.</summary>
       </Docs>
     </Member>
     <Member MemberName="WceMipsV2">
@@ -640,7 +640,7 @@
       </ReturnValue>
       <MemberValue>361</MemberValue>
       <Docs>
-        <summary>To be added.</summary>
+        <summary>MIPS little-endian WCE v2.</summary>
       </Docs>
     </Member>
   </Members>