Registerial cartography is the activity of systematically describing the registers that make up a language — with register in its original sense of a functional variety of a language, i.e. of the adaptation of the meaning-making resources of a language according to context of use. A register map of a language would thus show its composition of registers — of meanings at risk in the various cultural domains that constitute a culture. This variation according to use — register variation — is located along the cline of instantiation between the overall meaning potential of a language operating in the context of culture and the instantiation of this meaning potential unfolding as texts in contexts of situation.In this paper, I will report on a long-term register cartography project concerned with the analysis and description of the registers that collectively constitute the meaning potential of a language. The maps produced as part of the project are based on context in the first instance, since register variation is precisely variation according to context of use. Thus registers can be located within the map according to the “longitude and latitude” of context, i.e. according to the contextual parameters of field, tenor and mode. Here I will focus on a field-based map, more specifically one based on a typology of fields of activity — a characterizations of different goings-on in context. This typology differentiates eight primary types of field of activity, ‘expounding’, ‘reporting’, ‘recreating’, ‘sharing’, ‘doing’, ‘enabling’, ‘recommending’ and ‘exploring’, and their secondary and tertiary subtypes. I will then illustrate how texts operating in contexts characterized by these different fields of activity are organized semantically in terms of logico-semantic (rhetorical) relations (based on a version of RST, Rhetorical Structure Theory), showing that different relations are “at risk” depending on the nature of the field of activity. I will round off the paper by discussing how field-based maps of registers have and can be used in different areas of application.