I'm not real sure if even Nums knows this, but .thisgene when viewed by an opponent, actually shows the last active gene in the genome.
Once I realized this it was simple to make an ID system based on it. For same species recognition must have the same number of genes and same last active gene. Fortunately this worked well with Nums' idea of a constantly active viral defense at the end. Even if this value is discovered by another bot it requires constant storing in-order to maintain the deception. A further advantage is that the enemy would be hindered in effectively defending against viruses.
cond
*.robage 0 =
start
.thisgene .memloc store
stop
cond
*.eye5 50 >
*.memval *.genes !=
' must be both active and same number as last gene
start
-1 .shoot store
stop
cond
start
' little constant viral defense gene doubles as ID gene
*.genes .delgene
*.thisgene *.genes sub dup div
mult *.robage sgn mult store
.genes inc
stop
end
Endy ;)