Added the following configuration setting in the [BEHAVIOR] section:

useQuoteLineInitials=true
SlyEdit now prefixes quoted message lines with the previous author's initials to make it easier to identify who wrote various sections of a message and to make it easier to follow the conversation.  If desired, that behavior can be disabled by setting the above option to false.  When disabled, SlyEdit will quote message lines as before by simply prefixing them with " > ", as was done by IceEdit, DCT Edit, and other message editors in the early-mid 1990s.

ctrl/SlyEdit.cfg

@@ -6,6 +6,8 @@ inputTimeoutMS=300000
 ; so that they are complete but still look good when quoted.  If this option is
 ; disabled, then quote lines will simply be trimmed to fit into the message.
 reWrapQuoteLines=true
+; Whether or not to prefix the quote lines with the last author's initials
+useQuoteLineInitials=true
 ; 3rd-party startup scripts
 ;add3rdPartyStartupScript=
 ; JavaScript commands to run upon start of SlyEdit