The generic function
dde-client-advise-data is the default function called when an advise loop informs a client that the data monitored by the loop has changed. By default it does nothing, but it may be specialized on the object used as the key in dde-advise-start or dde-advise-start*, or on a client conversation class if the default key is used.
See Advise loops for information about DDE advise loops.
LispWorks User Guide and Reference Manual - 13 Feb 2015