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CONT: For pulp fibers, many of the diagnostic features of cell formation seen in wood samples are lost. However, positive identification is possible by following a logical sequence of exclusion, and finally comparing unknown fibers with authenticated fiber samples and/or photomicrographs. The technique is straightforward, especially where only a limited number of choices are possible. The principal diagnostic feature is the shape and orientation of the cell wall openings (pits) in softwood earlywood tracheids and hardwood vessels which are unique for each species.