Bornean Geometridae of the subfamily Ennominae are described: 429 species in 125 genera and 14 tribes. For each species a diagnosis and the geographical range are given and, where known, details of habitat preference and biology. Summary lists are provided of the new taxa described (3 tribes, 14 genera, 83 species and 5 subspecies) as well as of numerous other taxonomic changes. A checklist of all species summarises the fauna.
In an introductory section the family-group names applied within the subfamily are listed and reviewed. A commentary on the higher classification is presented, with reviews of the host- plant specialisations, ecology and geography of the group.
In the main text all except three genera are assigned to tribes, and both these tribes and their constituent genera are defined as far as possible on the basis of apomorphic (derived) characters.