  A new percentile-based rating scale P100 has recently been proposed to
describe the citation impact in terms of the distribution of the unique
citation values. Here I investigate P100 for 5 example datasets, two simple
fictitious models and three larger empirical samples. Counterintuitive behavior
is demonstrated in the model datasets, pointing to difficulties when the
evolution with time of the indicator is analyzed or when different fields or
publication years are compared. It is shown that similar problems can occur for
the three larger datasets of empirical citation values. Further, it is observed
that the performance evalution result in terms of percentiles can be influenced
by selecting different journals for publication of a manuscript.
