The contrastive use of this feature defines a major isogloss separating Jabo from Glebo. The yat border is the most important Bulgarian isogloss. Jan Goossens defines the northwest boundary of South East Limburgish at the "lijk-lich" isogloss. In Bulgaria the Yat border is considered the most important Bulgarian isogloss. However, as the dialect continuum shades towards Mayennais, there is a less clear isogloss. The differences between the two dialect result in a "clear isogloss". This makes this Limburgish isogloss the northernmost of all. In southern Brandenburg in eastern Germany, the isogloss runs by Halbe, Hermsdorf, Freidorf and Staakow. This also explains why a language border (isogloss) runs through Holungen. This is a result of the Centum-Satem isogloss, and later Grimm's Law. However, an "individual" isogloss may or may not have any coincidence with a language border. Similar to an isogloss, an isograph is a distinguishing feature of a writing system. However, the isogloss separates rather than connects points. One of the best-known isoglosses is the centum-satem isogloss. The Joret line () is an isogloss used in the linguistics of the .