While I cannot answer questions about running XDM over a DECnet, I can
say that the following defines must be added to the site.def before
building R5 before any X clients will work over a DECnet.

From site.def

#define ConnectionFlags -DTCPCONN -DUNIXCONN -DDNETCONN
#define ExtraLibraries -ldnet

Hoping this helps,

George

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