According to Pedraz-Delhaes, users evaluate both the product and the vendor on the basis of provided documentation. Thus, a question arises as to what quality characteristics should be taken into account when making a decision about accepting a given user manual. There are some proposals (e.g. ISO Std. 26513 and 26514) but they contain too many quality characteristics and lack orthogonality. The goal of this paper is to propose a simple quality model for user documentation, along with acceptance methods based on it. The model is to be orthogonal and complete. As a result, the COCA quality model is presented, which comprises four orthogonal quality characteristics: Completeness, Operability, Correctness, and Appearance. To check completeness, the proposed quality model has been compared to many other quality models that are directly or indirectly concerned with user documentation. Moreover, two acceptance methods are described in the paper: pure review based on ISO Std. 1028:2008, and Documentation Evaluation Test (it is a variant of Browser Evaluation Test) which is aimed at assessing  the operability of user documentation. Initial quality profiles have been empirically collected for both methods - they can be used when interpreting evaluation results obtained for a given user manual.