There are two boundaries, horizontal, and vertical. As part of their corporate strategy, firms must choose between being horizontally broad, vertically deep, or both. Firms with horizontal breadth have numerous product lines or types, whereas firms with vertical depth are integrated into various stages of the value chain. Generally, a firm's capabilities are specific to a particular scope direction, for example, marketing skills lead to horizontal breadth, and production expertise lead to vertical depth. A firm is horizontally broad when it utilises excess indivisible resources to expand into various products, and obtain scope economies. Horizontally broad firms leverage capabilities such as marketing skills, product knowledge, customer service, and reputation for their expansions. Scope economies, or economies of scope, describes the aspect of production wherein cost savings result from the scope of an enterprise, as opposed to the scale (see economies of scale). Meaning, there are economies of scope where it is less expensive for firms to combine two or more product lines into one, than it is to produce each product separately. Scope economies, wherein resources are synergistically used, has been found to improve firm performance. However, coordination, adjustment and execution costs related to producing products synergistically are limiting factors. A firm is vertically deep if they possess stronger capabilities than external producers, and thus can produce and distribute their good or service more efficiently internally - either upstream or downstream on the manufacturing chain. Vertically deep firms leverage capabilities such as production and process expertise, including technology selection, asset utilisation, and supply chain management. Vertical depth often improves a firm's governance of activities, and contributes to a beneficial exploitation of internal capabilities, but is limited by the costs of hierarchical management, such as monitoring and coordination. The concept of boundaries of can be linked to Coase's understanding of The Nature of the Firm, as it recognises that transaction costs are a significant factor in a firm's decision to outsource, or internally produce, but also considers other influences specific to firms, such as their relevant capabilities, and governance decisions. Importance of Boundaries A study of firms in France, illustrated how the number of employees and size of a firm directly impacts levels of productivity, wage and welfare within the organisation. In particular, an analysis of why firms with employees above the threshold of 50 declined in the early 2000s is conducted to further understand the correlation between size and output.