The problem with classifying Kajkavian within South Slavic stems in part from its structural differences from neighboring Shtokavian speeches as well as its historical closeness to Slovene speeches. Some Slavists maintain that when the separation of Western South Slavic speeches happened, they separated into four divergent groups — Shtokavian, Chakavian, Kajkavian and Slovene. As a result of this, throughout history Kajkavian has often been categorized differently than today. It was considered by many to be either a separate node altogether or a node categorized together with Slovene. Furthermore, very few isoglosses exist that separate all Slovene speeches from all other Western South Slavic dialects. Nor do innovations exist common to Kajkavian, Chakavian, and Shtokavian that would separate them from Slovene.