I cannot find an implementation of the Antenna rules ANT.3, ANT.4, ANT.5 in the KLayout Antenna Violation DRC script. Are they intentionally missing?

It seems like the actual antenna rule for the metals is executed by

ANT.16

. The (documented GF) rules are specified in an unusual manner, since usually the diffusion amount connected to the net is just calculated as part of the antenna rule and not specified as a separate antenna rule. It looks like the klayout deck rolls them into one rule, as is the usual way to do it, and then lists the rule as, e.g.,

ANT.16_i_ANT.3

, which I take to mean that the rule checks both

ANT.16(i)

and

ANT.3

.

Ah, yes, I only saw ANT.16 and didn't looked further.

@Philipp Gühring @Tim Edwards is correct.