/usr/lib/R/site-library/readMzXmlData/INDEX is in r-cran-readmzxmldata 2.8-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
| 1 2 3 4 | readMzXmlData-package   The readMzXmlData Package
readMzXmlDir            Reads recursively mass spectrometry data in
                        mzXML format.
readMzXmlFile           Reads mass spectrometry data in mzXML format.
 |