They’re probably talking about PI. Planetary materials come in T1-T4. No idea where that magical T5 comes from, though. Maybe a typo?
Anyway, a ship doing this would be twice pointless, as our planetary colonies are producing PI-materials already. First, because this entire line of skills and gameplay would be suddenly obsolete, second because if CCP doesn’t take the old system out to shoot it, no-one would use the new system because why the hell would you sit in your potentially vulnerable ship if you can produce PI in your safe, untouchable colonies?
If the OP was talking about something else, I’d like to hear a clarification, of course.