Library /sys$common/syshlp/pca$help.hlb PLOT, Data-kind qualifiers, /NONCOVERAGE  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    Tallies test non-coverage data along the horizontal axis. Every
    program unit that is not covered (is not executed at least once)
    gets a full-length histogram bar. Program units that are covered
    do not get histogram bars. To use this qualifier, you must have
    collected coverage or execution counts data with the SET COVERAGE
    or SET COUNTERS command.