In 1951 John L. Rich was the first to propose that the depositional settings of sediment accumulation on the shelf, slope, and bottom be (1) unda for shallow water overlying the shelf, (2) clino for the deeper water overlying the slope, and (3) fondo for the deepest water covering the bottom of the basin (Friedman (2001). Rich suggested the terms (1) undaform for any surface underlying an unda environment; (2) clinoform for any surface underlying a clino environment; (3) fondoform for any surface underlying a fondo environment. Thus "physical" accommodation comprises the space between sea floor and the "shelf equilibrium profile" of Swift and Thorne (1991), and the unda, lino and fondforms of of Rich (1951).

Following this approach Mitchum (1977) proposed that clinoform surface be used for the sloping depositional surface that is commonly associated with strata prograding into deep water.

References
Friedman, Gerald M., 2001, John L. Rich (1884–1956): Father of Clinoform, Undaform, and Fondoform," Abstract, Annual meeting of GSA Boston, Paper 24-0
Mitchum Jr., R.M., 1977, Seismic stratigraphy and global changes of sea level. Part 11: glossary of terms used in seismic stratigraphy. In: Payton, C.E. (Ed.), Seismic Stratigraphy––Applications to Hydrocarbon Exploration, vol. 26. A.A.P.G. Memoir, pp. 205–212.
Rich, J.L., 1951, Three critical environments of deposition and criteria for recognition of rocks deposited in each of them. Geol. Soc. Am. Bull. 62, 1-20.