This is a list of official and unofficial names for time spans in the geologic timescale and units of chronostratigraphy. Since many of the smallest subdivisions of the geologic timescale were in the past defined on regional lithostratigraphic units, there are many alternative names that overlap. The body concerned with standardizing the names of geochronologic units is the International Commission on Stratigraphy (ICS). In 2008 however, even though the Phanerozoic eon is almost completely divided into internationally recognizable units, local subdivisions are often still preferred over the international ones.