/usr/lib/R/site-library/GenomeInfoDb/INDEX is in r-bioc-genomeinfodb 1.0.2-2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
| 1 2 3 4 5 6 | GenomeInfoDb-helpers    List the supported seqname styles for all
                        supported organisms
fetchExtendedChromInfoFromUCSC
                        Fetching chromosomes info for some of the UCSC
                        genomes
rankSeqlevels           Assign sequence IDs to sequence names
 |