DDE is a message-based protocol used by Microsoft Windows.This document sometimes refers to the Windows message names (for example, WM_DDE_INITIATE) so that you  know how ESL DDE Support translates into messages.  Most of the ESL DDE events correspond directly to receipt of the like- named DDE message, and many of the ESL DDE subroutines post or send a DDE message.  You can always distinguish the message names from ESL DDE events by noting that the message names begin with "WM_"