Conventional descriptions of the Syriac script divide the variants along the lines of the church schism of the 6th century; the classical Estrangelo style was used up until the time of the church split, at which point followers of Nestoria in the East and of Jacob in the West developed two different writing styles as a symbol of their independence from one another. Most accounts also briefly mention a fourth style used by Christian Palestinians who spoke Aramaic.
However, Ayda Kaplan's doctoral thesis from the Catholic University of Louvain, "Syriac Paleography: The development of a method of expertise on the basis of the Syriac manuscripts of the British Library (Vth-Xth c.)" disputes this classification. Dr. Kaplan calls the earliest, formal, variant of the script (what is normally referred to as Estrangelo) "Syriac Monumental". This developed into "Monumental Semi-Courant", which was less formal so had the scope for wider use. Following this, a third style developed, called "Courant Semi-Monumental", which had fewer monumental features than the previous two, and finally, the Serto variant developed, which has no monumental features and is distinguishable from the previous three stytles.
Kaplan's research is based on her findings that several churches used the Monunmental Semi-Courant style; she suggests that it is no longer logical to divide the script's history along the same lines as church history when they do not overlap as well as previously thought.
Her findings are still relatively recent, but have been widely acknowledged among academics in the field.