| COG | Cluster of Orthologous Groups of proteins |
| HGT | Horizontal Gene Transfer |
| GFE | gene-family extension |
| Mbp | millions of base pairs |
| OT | Orientia tsutsugamushi |
| p.i. | the number of protein-coding gene families having more than one copy divided by the total number of COG-annotated protein-coding gene families |
| ave | average size of protein-coding gene families, including singletons |
| mp | the number of protein-coding gene families having more than two copies divided by the number of protein-coding gene families having more than one copy |