It should be re-emphasized that the distinctions between SMEs, LFs and giant MNCs is not simply about size. Rather, each of these categories groups together firms that share common organizational and behavioural traits that to some extent, but by means completely, correspond to variations in size.
An important implication of recognizing the LF segment is that the dual model of business segmentation, which is based on the 'polar' distinctions of tiny firms and giants, needs to be replaced with a 'triad' model of business segmentation. Such a triad model helps provide a better understanding of why both business segmentation and a size distribution of firms are realities of modern industrial economies. A triad model that specifically includes backbone firms, also recognizes that the boundaries between segments of firms are not absolute. That is, these boundaries are permeable to some degree as firms can enter and exit different segments.
You might wish to note two recent papers that seek to explain the differences between SMEs, LFs and giant MNCs while outlining the nature and implications of the triad model for business segmentation and local development. They are:
J. Patchell, R. Hayter and K. Rees 1999 Innovation and local development: the neglected role of large firms. In E. J. Malecki and P. Oinas (eds.) Making Connections: Technological Learning and Regional Economic Change, Aldershot: Ashgate, pp. 109-144.
R. Hayter, J. Patchell, and K. Rees 1999 Business Segmentation and Location Revisited: The Terra Incognita of Large Firms, Regional Studies (forthcoming).