The following papers are a good overview of Datakit and its
predecessors.
A. Fraser, "Towards a Universal Data Transport System," in IEEE
Journal on Selected Areas in Communications, vol. 1, no. 5, pp.
803-816, November 1983, doi: 10.1109/JSAC.1983.1145998.
A. G. Fraser, "Early experiments with asynchronous time division
networks," in IEEE Network, vol. 7, no. 1, pp. 12-26, Jan. 1993,
doi:10.1109/65.193084.
The latter mentions Plan 9 but only in passing.
Paul Ruizendaal <pnr(a)planet.nl> once said:
Probably you will see echoes of this in early Plan9
network code, but I have not studied that.
As someone how has studied Plan 9 extensively, though with no insider
knowledge, it's definitely noticeable.
"In the aftermath, perhaps the most valuable effect of dealing with
Datakit was to encourage the generalized and flexible approach to
networking begun in 8th edition Unix that is carried forward into Plan
9." - dmr (2004)
Cheers,
Anthony