diff --git a/xml/System/String.xml b/xml/System/String.xml
index 9034900baba..a9126ac48c8 100644
--- a/xml/System/String.xml
+++ b/xml/System/String.xml
@@ -3557,10 +3557,10 @@ You can download the [Sorting Weight Tables](https://www.microsoft.com/download/
         <Parameter Name="str1" Type="System.ReadOnlySpan&lt;System.Char&gt;" Index="1" FrameworkAlternate="netcore-3.0" />
       </Parameters>
       <Docs>
-        <param name="str0">To be added.</param>
-        <param name="str1">To be added.</param>
-        <summary>To be added.</summary>
-        <returns>To be added.</returns>
+        <param name="str0">The first read-only character span to concatenate.</param>
+        <param name="str1">The second read-only character span to concatenate.</param>
+        <summary>Concatenates the string representations of two specified read-only character spans.</summary>
+        <returns>The concatenated string representations of the values of <paramref name="str0" /> and <paramref name="str1" />.</returns>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -3723,11 +3723,11 @@ You can download the [Sorting Weight Tables](https://www.microsoft.com/download/
         <Parameter Name="str2" Type="System.ReadOnlySpan&lt;System.Char&gt;" Index="2" FrameworkAlternate="netcore-3.0" />
       </Parameters>
       <Docs>
-        <param name="str0">To be added.</param>
-        <param name="str1">To be added.</param>
-        <param name="str2">To be added.</param>
-        <summary>To be added.</summary>
-        <returns>To be added.</returns>
+        <param name="str0">The first read-only character span to concatenate.</param>
+        <param name="str1">The second read-only character span to concatenate.</param>
+        <param name="str2">The third read-only character span to concatenate.</param>
+        <summary>Concatenates the string representations of three specified read-only character spans.</summary>
+        <returns>The concatenated string representations of the values of <paramref name="str0" />, <paramref name="str1" /> and <paramref name="str2" />.</returns>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -3901,12 +3901,12 @@ You can download the [Sorting Weight Tables](https://www.microsoft.com/download/
         <Parameter Name="str3" Type="System.ReadOnlySpan&lt;System.Char&gt;" Index="3" FrameworkAlternate="netcore-3.0" />
       </Parameters>
       <Docs>
-        <param name="str0">To be added.</param>
-        <param name="str1">To be added.</param>
-        <param name="str2">To be added.</param>
-        <param name="str3">To be added.</param>
-        <summary>To be added.</summary>
-        <returns>To be added.</returns>
+        <param name="str0">The first read-only character span to concatenate.</param>
+        <param name="str1">The second read-only character span to concatenate.</param>
+        <param name="str2">The third read-only character span to concatenate.</param>
+        <param name="str3">The fourth read-only character span to concatenate.</param>
+        <summary>Concatenates the string representations of four specified read-only character spans.</summary>
+        <returns>The concatenated string representations of the values of <paramref name="str0" />, <paramref name="str1" />, <paramref name="str2" /> and <paramref name="str3" />.</returns>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -4073,9 +4073,9 @@ You can download the [Sorting Weight Tables](https://www.microsoft.com/download/
         <Parameter Name="value" Type="System.Char" Index="0" FrameworkAlternate="netcore-2.1;netcore-2.2;netcore-3.0;netstandard-2.1" />
       </Parameters>
       <Docs>
-        <param name="value">To be added.</param>
-        <summary>To be added.</summary>
-        <returns>To be added.</returns>
+        <param name="value">The character to seek.</param>
+        <summary>Returns a value indicating whether a specified character occurs within this string.</summary>
+        <returns><see langword="true" /> if the <paramref name="value" /> parameter occurs within this string; otherwise, <see langword="false" />.</returns>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -4121,8 +4121,7 @@ You can download the [Sorting Weight Tables](https://www.microsoft.com/download/
       <Docs>
         <param name="value">The string to seek.</param>
         <summary>Returns a value indicating whether a specified substring occurs within this string.</summary>
-        <returns>
-          <see langword="true" /> if the <paramref name="value" /> parameter occurs within this string, or if <paramref name="value" /> is the empty string (""); otherwise, <see langword="false" />.</returns>
+        <returns><see langword="true" /> if the <paramref name="value" /> parameter occurs within this string, or if <paramref name="value" /> is the empty string (""); otherwise, <see langword="false" />.</returns>
         <remarks>
           <format type="text/markdown"><![CDATA[  
   
@@ -4185,10 +4184,10 @@ You can download the [Sorting Weight Tables](https://www.microsoft.com/download/
         <Parameter Name="comparisonType" Type="System.StringComparison" Index="1" FrameworkAlternate="netcore-2.1;netcore-2.2;netcore-3.0;netstandard-2.1" />
       </Parameters>
       <Docs>
-        <param name="value">To be added.</param>
-        <param name="comparisonType">To be added.</param>
-        <summary>To be added.</summary>
-        <returns>To be added.</returns>
+        <param name="value">The character to seek.</param>
+        <param name="comparisonType">One of the enumeration values that specifies the rules to use in the comparison.</param>
+        <summary>Returns a value indicating whether a specified character occurs within this string, using the specified comparison rules.</summary>
+        <returns><see langword="true" /> if the <paramref name="value" /> parameter occurs within this string; otherwise, <see langword="false" />.</returns>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -4219,10 +4218,10 @@ You can download the [Sorting Weight Tables](https://www.microsoft.com/download/
         <Parameter Name="comparisonType" Type="System.StringComparison" Index="1" FrameworkAlternate="netcore-2.1;netcore-2.2;netcore-3.0;netstandard-2.1" />
       </Parameters>
       <Docs>
-        <param name="value">To be added.</param>
-        <param name="comparisonType">To be added.</param>
-        <summary>To be added.</summary>
-        <returns>To be added.</returns>
+        <param name="value">The string to seek.</param>
+        <param name="comparisonType">One of the enumeration values that specifies the rules to use in the comparison.</param>
+        <summary>Returns a value indicating whether a specified string occurs within this string, using the specified comparison rules.</summary>
+        <returns><see langword="true" /> if the <paramref name="value" /> parameter occurs within this string, or if <paramref name="value" /> is the empty string (""); otherwise, <see langword="false" />.</returns>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -6318,9 +6317,9 @@ String 'This is a string.' in domain 'NewDomain': 75CC8236
         <Parameter Name="value" Type="System.ReadOnlySpan&lt;System.Char&gt;" Index="0" FrameworkAlternate="netcore-3.0" />
       </Parameters>
       <Docs>
-        <param name="value">To be added.</param>
-        <summary>To be added.</summary>
-        <returns>To be added.</returns>
+        <param name="value">A read-only character span.</param>
+        <summary>Returns the hash code for the provided read-only character span.</summary>
+        <returns>A 32-bit signed integer hash code.</returns>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -6351,9 +6350,9 @@ String 'This is a string.' in domain 'NewDomain': 75CC8236
         <Parameter Name="comparisonType" Type="System.StringComparison" Index="0" FrameworkAlternate="netcore-2.0;netcore-2.1;netcore-2.2;netcore-3.0;netstandard-2.1" />
       </Parameters>
       <Docs>
-        <param name="comparisonType">To be added.</param>
-        <summary>To be added.</summary>
-        <returns>To be added.</returns>
+        <param name="comparisonType">One of the enumeration values that specifies the rules to use in the comparison.</param>
+        <summary>Returns the hash code for this string using the specified rules.</summary>
+        <returns>A 32-bit signed integer hash code.</returns>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -6383,10 +6382,10 @@ String 'This is a string.' in domain 'NewDomain': 75CC8236
         <Parameter Name="comparisonType" Type="System.StringComparison" Index="1" FrameworkAlternate="netcore-3.0" />
       </Parameters>
       <Docs>
-        <param name="value">To be added.</param>
-        <param name="comparisonType">To be added.</param>
-        <summary>To be added.</summary>
-        <returns>To be added.</returns>
+        <param name="value">A read-only character span.</param>
+        <param name="comparisonType">One of the enumeration values that specifies the rules to use in the comparison.</param>
+        <summary>Returns the hash code for the provided read-only character span using the specified rules.</summary>
+        <returns>A 32-bit signed integer hash code.</returns>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -6423,10 +6422,20 @@ String 'This is a string.' in domain 'NewDomain': 75CC8236
       </ReturnValue>
       <Parameters />
       <Docs>
-        <summary>Returns a reference to the first element of the string.</summary>
-        <returns>A pinnable reference to the first element of the string as a read-only char.</returns>
-        <remarks>To be added.</remarks>
-        <exception cref="T:System.NullReferenceException">The string is <see langword="null" />.</exception>
+        <summary>Returns a reference to the element of the string at index zero.</summary>
+        <returns>A character representing the reference to the element of the string at index zero.</returns>
+        <remarks>
+          <format type="text/markdown">
+            <![CDATA[
+
+## Remarks
+
+The `GetPinnableReference` method returns a character that can be used for pinning a <xref:System.String> in memory. It is required to support the use of a <xref:System.String> within a fixed statement.
+
+          ]]>
+          </format>
+        </remarks>
+        <exception cref="T:System.NullReferenceException">The string is null.</exception>
       </Docs>
     </Member>
     <Member MemberName="GetTypeCode">