The system topic provides a context for information that might be of general interest to any partners in a DDE transaction. Server applications are encouraged to support the system topic at all times. The string used for the system topic is defined in the PM header files as SZDDESYS_TOPIC.
DDE applications should request an exchange on the system topic with a zero-length application name when they start up, to find out what kinds of information other DDE-capable programs can provide.
The system topic must support the items in the following table as well as any other items the application uses:
旼컴컴컴컴컴컴컴컴컴컴컴컴쩡컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� 쿔tem 쿏escription � 쳐컴컴컴컴컴컴컴컴컴컴컴컴탠컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� 쿞ZDDESYS_ITEM_FORMATS 쿌 list of strings equivalent to � � 쿎F_CONSTANTS with the CF_ prefix � � 퀁emoved. For example, CF_TEXT = � � 쿟EXT. � 쳐컴컴컴컴컴컴컴컴컴컴컴컴탠컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� 쿞ZDDESYS_ITEM_HELP 쿌 text description of the server's � � 쿏DE services. � 쳐컴컴컴컴컴컴컴컴컴컴컴컴탠컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� 쿞ZDDESYS_ITEM_PROTOCOLS 쿌 list of protocol names the server� � 퀂upports. A protocol is a set of � � 쿏DE execute commands, each having a� � 퀂tandard meaning. � 쳐컴컴컴컴컴컴컴컴컴컴컴컴탠컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� 쿞ZDDESYS_ITEM_RESTART 쿌 string that a client can pass to � � 쿏osExecPgm to invoke a server that � � 쿶s not running. � 쳐컴컴컴컴컴컴컴컴컴컴컴컴탠컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� 쿞ZDDESYS_ITEM_RTNMSG 쿞upporting detail for the most � � 퀁ecently issued WM_DDE_ACK message.� � 쿟his is useful when more than 8 � � 쿫its of application-specific return� � 쿬ode are required. � 쳐컴컴컴컴컴컴컴컴컴컴컴컴탠컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� 쿞ZDDESYS_ITEM_SECURITY 쿌 security-sensitive server � � 쿪pplication. Any client can � � 쿶nitiate a conversation with a � � 퀂ecurity-sensitive server, but the � � 퀂erver responds only to the � � 쿞ecurity topic. Typically, the � � 퀂erver requires a password from the� � 쿬lient before any further data � � 쿮xchange can take place. � 쳐컴컴컴컴컴컴컴컴컴컴컴컴탠컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� 쿞ZDDESYS_ITEM_STATUS 쿌n indication of the current status� � 쿽f the server: "Ready" or "Busy". � 쳐컴컴컴컴컴컴컴컴컴컴컴컴탠컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� 쿞ZDDESYS_ITEM_SYSITEMS 쿌 list of the items supported under� � 퀃he system topic by this server. � 쳐컴컴컴컴컴컴컴컴컴컴컴컴탠컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� 쿞ZDDESYS_ITEM_TOPICS 쿌 list of the topics currently � � 퀂upported by the application. This � � 쿬an vary from moment to moment. � 읕컴컴컴컴컴컴컴컴컴컴컴컴좔컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴�
Individual elements of lists should be delimited by tabs, as in the DDEFMT_TEXT format.