Previously transport networks were typically static, lacked flexibility, and required long planning times when deploying new services. Network Providers and Service Providers have embraced technologies that allow separation of data plane and control plane, distributed signaling for path setup and protection, and centralized path computation for service planning and traffic engineering. Although these technologies provide significant benefits, they do not meet the growing need for network programmability, automation, resource sharing, and service elasticity necessary for meeting customer demands and evolving Internet applications By combining the aforementioned capabilities with network resource virtualization and abstraction mechanisms, available via well- defined customer interfaces, providing significant operational benefits to meet the growing demands from customers and applications. The work effort investigating this problem space is known as Abstraction and Control of Transport Networks (ACTN). This document provides an ACTN problem description, scope of work, and outlines the core requirements to facilitate network resource virtualization and resource slicing for customers and applications, across Service Provider and Network Provider transport network infrastructure.