Data over DC power lines?  How about parasite power derived from the
communication line?  It's easier to half wave rectify and filter data to
power a PIC than to drive data into a battery.  Maybe it's just
perspective or nomenclature.  Have you ever seen
www.dallassemiconductor.com and their 1-wire (tm) chips? Cool.  And,
"Remember: credit card orders are limited to 10 pieces or less except
for iButton products".  Can you believe that from a major chip manf.?

Don