In the context of Blocks, which feature includes items like 'value type' and 'signal'?

The correct choice highlights the nature of Blocks in the context of systems modeling. Structural features are fundamental characteristics that define the composition and arrangement of a Block. This definition encompasses properties such as 'value type', which indicates the type of data that a block can hold, and 'signal', which refers to a type of value that can be exchanged between components in a system.

These structural features provide a framework for understanding how individual elements can be designed to interact, contributing to the overall architecture of the model. In systems modeling, Blocks serve as building components that encapsulate both data and behavior, but the structural features focus on the definitions and classifications of what makes up those Blocks.

Behavioral features, while important, relate more to the actions and dynamics of the Block rather than its structural composition. Element definitions refer to the broader concept of how items are identified and named within the modeling context, while constraints deal with the rules that limit or guide the structure and behavior of elements. Hence, the emphasis on structural features, including 'value type' and 'signal', is central to understanding how Blocks are constructed and function within a model.