"FOREWORD: The standardization program of the American Petroleum Institute relative to oil field equipment at present embraces ten main classes of materials. Where necessary and desirable for convenient use@ each class has been subdivided into subjects. Separate specifications may be issued on each subject@ and each should be filed in the Handbook under the general class to which it belongs. Each specification will be issued as a separate unit and identified by the Committee number@ with alphabetical sub-divisions when needed. When a specification is amended or revised@ it will be re-issued under its old number@ with a new date and edition number; for example@ ""A. P. I. Pipe Specification No. 5-A. 2nd Edition@ Sept.@ 1926@"" will indicate that this specification has been revised from the first edition. In case a large supply of specifications is on hand@ a supplement containing the changes and modifications may be issued@ and later incorporated in a revised edition of the specification. A special Committee has been appointed on the standardization of each class of material; and the Committee personnel@ published separately@ should be inserted under the proper subject. The demand for A. P. I. Specifications@ handbook size@ has been so great that the printing expense has attained considerable proportions. It was@ therefore@ decided at the Seventh Annual Meeting of the Institute at Tulsa. Okla.@ December@ 1926@ to charge for the specifications. A list (and status) of all A. P. I. Codes and Posters on Recommended Field Practice is contained herein. In this Bulletin are listed the names of all companies or individuals licensed to use the A. P.I. Monogram in accordance with the various specifications. It Should be noted that the list of licensees is constantly being enlarged. This printing contain the list of ail such companies licensed as of Oct. 5@ 1928."