// The target range is the specific phrase in the introduction's first paragraph
DocumentRange[] foundRanges = richEditControl.Document.FindAll("an extensive problem in hardware and architecture is the construction of the emulation of checksums", SearchOptions.None);
if (foundRanges.Length > 0)
{
    // Create a new comment
    Comment comment = richEditControl.Document.Comments.Create(foundRanges[0], "Johnson Alphonso D", new DateTime(2014, 4, 25));
}

' The target range is the specific phrase in the introduction's first paragraph
Dim foundRanges() As DocumentRange = richEditControl.Document.FindAll("an extensive problem in hardware and architecture is the construction of the emulation of checksums", SearchOptions.None)
If foundRanges.Length > 0 Then
    ' Create a new comment
    Dim comment As Comment = richEditControl.Document.Comments.Create(foundRanges(0), "Johnson Alphonso D", New Date(2014, 4, 25))
End If

Document document = richEditControl.Document;

if (document.Comments.Count > 0)
{
    // Create a new comment nested to the second comment in the collection
    Comment nestedComment = document.Comments.Create("Brian Zetc", DateTime.Now, document.Comments[1]);

    // Add text to the newly created comment
    SubDocument nestedCommentDocument = nestedComment.BeginUpdate();
    DocumentRange textRange = nestedCommentDocument.InsertText(nestedCommentDocument.CreatePosition(0),
    "Suffix trees are comprehensively reviewed in Wikipedia");
    nestedComment.EndUpdate(nestedCommentDocument);
}

Dim document As Document = richEditControl.Document

If document.Comments.Count > 0 Then
    ' Create a new comment nested to the second comment in the collection
    Dim nestedComment As Comment = document.Comments.Create("Brian Zetc", Date.Now, document.Comments(1))

    ' Add text to the newly created comment
    Dim nestedCommentDocument As SubDocument = nestedComment.BeginUpdate()
    Dim textRange As DocumentRange = nestedCommentDocument.InsertText(nestedCommentDocument.CreatePosition(0), "Suffix trees are comprehensively reviewed in Wikipedia")
    nestedComment.EndUpdate(nestedCommentDocument)
End If

Document document = richEditControl.Document;

int commentCount = document.Comments.Count;
if (commentCount > 0)
{
    // The target comment is the first one
    Comment comment = document.Comments[0];
    if (comment != null)
    {
        // Open the comment for modification
        SubDocument commentDocument = comment.BeginUpdate();

        // Add text to the comment range
        commentDocument.InsertText(commentDocument.CreatePosition(0),
            "J. Taylor, Enabling Voice - over - IP and RAID with sofa, in Proceedings of NOSSDAV, Oct. 1994.\r\n" +
            @"R.Tarjan, S.Shenker, J.Gray, A.Einstein, Q.Thomas, and X.Sato, ""Deconstructing operating systems with flanchedripper"", in Proceedings of INFOCOM, Mar. 2000.");

        // End the comment update
        comment.EndUpdate(commentDocument);
    }
}

Dim document As Document = richEditControl.Document

Dim commentCount As Integer = document.Comments.Count
If commentCount > 0 Then
    ' The target comment is the first one
    Dim comment As Comment = document.Comments(0)
    If comment IsNot Nothing Then
        ' Open the comment for modification
        Dim commentDocument As SubDocument = comment.BeginUpdate()

        ' Add text to the comment range
        commentDocument.InsertText(commentDocument.CreatePosition(0), "J. Taylor, Enabling Voice - over - IP and RAID with sofa, in Proceedings of NOSSDAV, Oct. 1994." & ControlChars.CrLf & "R.Tarjan, S.Shenker, J.Gray, A.Einstein, Q.Thomas, and X.Sato, ""Deconstructing operating systems with flanchedripper"", in Proceedings of INFOCOM, Mar. 2000.")

        ' End the comment update
        comment.EndUpdate(commentDocument)
    End If
End If

Document document = richEditControl.Document;
int commentCount = document.Comments.Count;

if (commentCount > 0)
{

    document.BeginUpdate();
    // The target is the second last comment
    Comment comment = document.Comments[document.Comments.Count - 1];

    // Change the comment's name, author and creation date
    comment.Name = "Reference";
    comment.Date = DateTime.Now;
    comment.Author = "Vicars Annie";
    document.EndUpdate();
}

Dim document As Document = richEditControl.Document
Dim commentCount As Integer = document.Comments.Count

If commentCount > 0 Then

    document.BeginUpdate()
    ' The target is the second last comment
    Dim comment As Comment = document.Comments(document.Comments.Count - 1)

    ' Change the comment's name, author and creation date
    comment.Name = "Reference"
    comment.Date = Date.Now
    comment.Author = "Vicars Annie"
    document.EndUpdate()
End If

Document document = richEditControl.Document;
if (document.Comments.Count > 0)
  {
   //Remove the fourth document comment
   document.Comments.Remove(document.Comments[3]);
  }

Dim document As Document = richEditControl.Document
If document.Comments.Count > 0 Then
'Remove the fourth document comment
document.Comments.Remove(document.Comments(3))
End If