can the “series I” perform 64-addressing in order to make use of the SH & SL address?
Yes, you’d config DH with the SH value from the destination, and DL with the SL value. This sets up unicast.
Here’s a good article to use for reference:
http://www.digi.com/support/kbase/kbaseresultdetl.jsp?id=2187
The 802.15.4 OEM manual would be a good resource as well, which can be found under the Documentation area for 802.15.4 products on our Support site.
mucho gracias! as they say, RTFM, yes 