Jean St. Thomas and I had a very gratifying working association for more than two years during the mid-fifties. St. Thomas was obsessed with the desire to do something about the problem of codification. It was apparent that he had a keen insight into the re-quirement and the problem. He made serious attempts to verbalize the nature and the scope of the problem in various papers. St. Thomas reflected later that his early proposals were "premature, incomplete, and unsuitable for indexing." This statement of construc-tive self-criticism was presented by a man who is earnestly involved with an unquenchable desire for a workable solution. St. Thomas probed, discussed, revised, re-considered and has currently presented a base from which a system of codification can now be initiated. I was requested by the Society of Photographic Instrumentation Engineers to review and introduce the revised work and to add my endorsement. I am delighted to comply: The codification of Photo-Optical Instrumentation Engineering under the Dewey Decimal System, as proposed by St. Thomas, is the result of the analysis and selection of a currently recognized classification system to serve as the structure from which an immediate and workable solution to the indexing of "hardware" can be accomplished for the systematic storage and retrieval of information. The practical experiences gained from other serious attempts to codify the field has been considered in the St. Thomas proposal. The accelerated growth of technological knowledge is creating an ever increasing demand for the service of storing and retrieving PhotoOptical Instrumentation information. It is recommended that the proposal receive the immediate attention of the responsible parties who are in the authorized position to initiate and execute a plan of action.