01 See #TiSDD chapter 3, Basic service design tools, for an overview of possible system map types.
02 The mapping of systems is particularly useful in the context of product service system innovation. See, for example, Morelli, N. (2006). “Developing New Product Service Systems (PSS): Methodologies and Operational Tools.” Journal of Cleaner Production, 14(17), 1495-1501.
“System maps” is an umbrella term for different visualizations of systems: stakeholder maps, value network maps, and ecosystem maps.  All of these can be created from various perspectives. A system can be mapped from a customer’s perspective, including competitors within their consideration set as well as external players that might not have a direct relationship with the organization. Alternatively, a system map can focus on the business itself and visualize external stakeholders involved in support processes: as an alternative or addition, it could illustrate various departments and business units. 
System maps have obvious relationships to other tools in service design, such as personas and journey maps. Personas can be integrated as stakeholders within a system map. This becomes particularly interesting when customers have contact with one another or when there are (potential) conflicts between different customer groups. As stakeholders can be part of journey maps (e.g., through a specific lane on the journey map that summarizes which internal and/or external stakeholders are involved at each step), you can use this data as a basis for a system map to understand relationships between the involved players within a particular journey.
As system maps can become very messy, you should maintain a clear focus for a map. Don’t try to visualize every stakeholder you can think of on the same stakeholder map; it’s more useful to make various maps for different purposes. Such maps could, for example, focus on internal stakeholders to visualize the formal and informal internal network, focus on one specific experience (e.g., based on a journey map) to get an overview of the system of actors, or focus on financial transactions between stakeholders to understand financial streams within a system.
System maps are an excellent tool to synthesize your research data and to identify promising interview partners. Remember that research is iterative, and it makes sense to use these maps to find gaps in your research data which you can investigate in later research iterations.