Negation of the passive participles
The negation verb 
tm is used to negate the passive participle forms. It is notable that the negative verb always takes the form of what it negates while the original verb turns into a negatival complement.
tAw nb(w) tmm xnd st
All lands which had not been trodden.
The negating perfective passive participle is by using the geminated form tmm; as for the original verb xnd, it is a negatival complement.