EFERENCE 1 is concerned with establishing a general formulation for studying the librational dynamics of a class of spacecraft characterized by an arbitrary number of flexible deploying appendages cantilevered to a rigid central core body. The configuration is unique in that it includes both beam and plate appendages. Nevertheless, it is not clear that the material presented by Modi and Ibrahim represents an extension to results already available in the literature. In particular, the large angle librational equations for this class of problem are fully derived and presented in Refs. 2-51 and apply whether the appendages are beam-like or plate-like. Similarly, the complementary equations governing vibration of beam-like appendages are worked out in greater detail in Refs. 3-5, while appendage dynamics associated with the plate model is given in Ref. 6. In addition to the formulations of the governing equations discussed above, it is evident as well from the literature5'7'8 that computer solutions have been obtained and parameter studies carried out for this class of problem when appendage beams only are involved. The existing software readily accomodates the introduction of other categories of appendages. For the case considered in Ref. 1, a single additional subroutine for the plate vibrations is all that is required. Specific comments follow concerning the limitations of the appendage dynamics given in Ref. 1. First, however, it should be pointed out that the appendage configurations are not as general as claimed. The analysis presented does not account for variations in mass density, flexural rigidity or crosssectional area of the beam/plate structures as stated in the Introduction in numbered paragraph 3 under essential features. To do so, when evaluating kinetic and strain energies over the domain of a continuum, these properties must all be retained within the integration, even after discretization of the distributed coordinates. Based on the strain energy expressions presented by the authors, it is evident that only uniform beams and plates are considered.