The concept of a shape is referenced throughout the spec. However, it is not defined so the reader would need to examine the ShEx and/or SHACL specs to understand what they are. I think its worth providing a concise definition in this specification so that reader does not need to read ShEx and/or SHACL in order to understand the concept. Even linking to https://www.w3.org/TR/shacl/#dfn-shape would probably require the reader to get into the details of the SHACL spec to really understand what a shape is. If you provide a simple definition then the reader can continue in this specification and only refer to the authoritative definitions when they want to get into the details.
https://github.com/shapetrees/specification/blob/2d084ec3263cecf060f275a6ceead216c236e000/spec.bs#L130
The concept of a shape is referenced throughout the spec. However, it is not defined so the reader would need to examine the ShEx and/or SHACL specs to understand what they are. I think its worth providing a concise definition in this specification so that reader does not need to read ShEx and/or SHACL in order to understand the concept. Even linking to https://www.w3.org/TR/shacl/#dfn-shape would probably require the reader to get into the details of the SHACL spec to really understand what a shape is. If you provide a simple definition then the reader can continue in this specification and only refer to the authoritative definitions when they want to get into the details.