sending strings data into IPfix stream

Hello,
Not sure if this is the right list for this type of message ...
I am developing an IPFIX exporter. It exports IP flows, and I'd like now 
to export some extra information (strings) about the machines on the LAN 
(the hostname of the machine, and others information ...)
What is the right way to do that (IPFIX fields to use, template options 
or not ...)
Thank you very much in advance. Regards
T. Descombes