The goal of the paper is to analyze the relation between the data (the set of all possible input-output mapping generated by an OT system) and the theory (the ranking conditions that generate each grammar) for an OT system (abbreviated SHABC) that includes crucial constraints and candidates from Headed Agreement By Correspondence (Iacoponi, 2015) using property theory (Alber and Prince, in prep., a.o.).Such an analysis is important for three reasons. First, since the analysis concerns the structure of a basic HABC typology, it significantly facilitates the study of the differences between HABC and the theories which it extends, namely ABC, and ABCD (Hansson 2001(Hansson /2010Rose & Walker 2004;Bennett 2013). Second, as shown in Alber and Prince (in prep.) and in Bennett, DelBusso and Iacoponi (2016), the study of the properties of a system is useful when the system is extended to include more constraints or candidates. Finding the basic structure of a typology not only deepens our understanding of the theory, but it also significantly facilitates the analysis of its extended sub-systems, allowing us to rigorously study the effect the different components (such as classes of candidates or specific constraints) have on the theory. Finally, by using the property analysis of a typology, it is possible to validate the universality of the support used to obtain the typology (see Alber, DelBusso and Prince, 2015).The paper is organized as follows. In section 1, I introduce the two core theories the paper builds on: Headed Agreement By Correspondence (HABC) and the formal properties of OT typologies. Section 2 contains the definitions of the constraints and of the candidate set. Section 3 discusses the typology, and the relation between its intensional and extensional properties. /2010, 2007 Rose 2000 Rose , 2011McCarthy, 2007;Bennett 2013 Bennett , 2014; and others) is a theory developed to account for harmony and dissimilation. In ABC, harmony is caused by two families of constraints: correspondence constraints that demand segments with a specific feature value to be in a correspondence relation, and Ident-CC/VV constraints, that ban segments in correspondence that have different feature values. Harmony occurs when at least one constraint that demands segments to correspond, and one constraint that demand segments in correspondence to be identical outrank a relevant set of Ident-IO constraints.