Well, you should try yourself, but I can give you the answer right now, you can't it will cause CTD's upon opening the building scroll.
There is however a different way to achieve what you want to achieve ( but it will be a bit of work depending on howmany units you want to do this for) note that this will effectivly mean you will have a maxiumum available of 1
put this entry in the barrack
Code:
"Andalusian Spearmen" 0.5 0.1 0.5 0 requires factions { russia, novgorod, } and event_counter HEAVY_MAIL_ARMOR 1 and hidden_resource aor_iberia
and this entry in the heavy_armourer
Code:
"Andalusian Spearmen" 0.5 0.1 0.5 0 requires factions { russia, novgorod, } and event_counter HEAVY_MAIL_ARMOR 1 and hidden_resource aor_iberia
This will give you 1 unit of Andalousian Spearmen if you have both the Heavy Armourer and the barracks in a settlement ( with a refresh of 0.2 ). Note that this unit won't show up in any of the buildings scrolls but it will become available for recruitment.