## 3 Results
### Literature Analysis
#### 3.1.3 Cross-Cutting Perspectives  
Cross-cutting perspectives are motivated by generic system theory. Product lifecycles are based on cognition--leading to invention--utilized for innovation and brought  
Figure 3: Integrative perspectives of the product lifecycle: (**a**) product, production and business perspectives represented by chain-like lifecycle visualizations (detailed in [48]); (**b**) product and service lifecycles integrated into product–service systems (adopted from [54]; (**c**) integrative view with macro-cycle and internal micro-cycles in each phase enabling Smart Manufacturing (based on [55]).  
into use by diffusion [57]. The concept of CE emphasizes the benefits that can be gathered from EoL: while value creation is typically focused on engineering, production and use/operation phases, business models shall even cover the recycling phase in future. Thus, sustainability is ensured not only by policy making, but with its intrinsic business value. For sustainability, circular material flow is essential. Different recycling options can be scheduled in early product development phases, but innovation is also possible in later phases (see Figure 4a [58]). For instance, new repair technologies can be applied for cars (product instances) in their use phase, which are not yet available in development times (when the product class is specified). For the EoL phase, several frameworks are conceptualized to cover options from the reuse of products to recovering material for energy generation [59; 60; 61]. The differentiation of product class and product instances is implicitly assumed in some economic models. Basic models are provided in strategic management [62; 63]. They are focused on economic factors, such as turnover and profit, which are driven by the number of product instances. Assuming combined product and service offerings, the temporal differences are obvious: while at the end of production the delivery of new product instances to customers stops, services are still delivered with respect to product instances in operations (see Figure 4b [64]). This phase can be significantly longer than the BoL phase; product owners might change and instances might be subject to change [65]. Thus, the enabling of innovation in MoL and EoL phases is a challenge, as is opportunity in early phases (anticipation of \"to-be\" product life) and \"as-is\"/\"as-was\" information in later phases of system lifecycle management [66].  
The following requirements add up to the items mentioned in Sections 3.1.1 and 3.1.2:  
**Finding 8**.: _Targeting Circular Economy, circularity needs to be understood as the macro-perspective of a product lifecycle, its information and its material._  
Sustainability as a relevant requirement needs to be implemented into all other perspectives aligning toward Circular Economy, incorporating \"sustainable thinking\" into business models targeting business opportunities, even in the EoL. Setting anchoring points or cross-cutting topics, such as innovation management, technology management, material development, enables contribution from enabling fields.  
**Finding 9**.: _The intrinsic perspective needs to be complemented by the economic perspective from business modeling to market saturation that correlates with the number of product instances._  
Figure 4: Cross-cutting perspectives of the product lifecycle: (**a**) material flow in Circular Economy with innovation opportunities along all lifetime phases (based on [58]); (**b**) economic perspective of product–service systems, highlighting temporal effects of Product Creation (time of series production) and continuation of service in after-sales (based on [64]).  
With respect to product classes, an intrinsic definition of phases from product ideas to recycling is reasonable (cf. Section 3.1.1). Investments are taken as long as a product class is developed, and realization is prepared. Return of investment starts with realization of product instances and delivery of services.