There are many approaches that propose the use of measures for assessing the quality of conceptual schemas. Many of these measures focus purely on the syntactic aspects of the conceptual schema diagrams, e.g. their size, their shape, etc. Similarities among different measures may be found both at the intra-model level (i.e., several measures over the same type of diagram are defined following the same layout) and at the inter-model level (i.e., measures over different types of diagrams are similar considering an appropriate metaschema correspondence). In this paper we analyse these similarities for a particular family of diagrams used in conceptual modelling, those that can be ultimately seen as a combination of nodes and edges of different types. We propose a unifying measuring framework for this family and illustrate its application on a particular type, namely business process diagrams.