There are new geosynthetic products entering the marketplace for which the manufacturers seek to classify their products as geomembranes. These products challenge the current ASTM definition of a geomembrane. ASTM D4439 "Standard Terminology for Geosynthetics" currently defines a geomembrane as "an essentially impermeable geosynthetic composed of one or more synthetic sheets". For example, D35 committee members must consider if any of the following products are geomembranes: laminate or coated geotextile; polymer infused geotextile; concrete infused geotextile or concrete sandwiched between two geotextiles Each of the above may function as a geomembrane, yet fail to meet the current ASTM definition. Revising the current geomembrane definition to include these products would result in ASTM standards that would no longer be applicable for testing a wide range of geomembrane material. Although ASTM D35's primary responsibility is to develop good applicable standards for geosynthetic materials, the committee is aware that numerous geosynthetic terms and their definitions have significant applications beyond the responsibility of ASTM. A revision of the geomembrane definition to include these products would conflict with the present understanding of a geomembrane product for those within and outside the geosynthetic field. However, the manufacturers of these new products want their product(s) classified as a "geomembrane". To better understand why they seek this classification, an understanding of geosynthetic history is helpful. The development of ASTM standard test methods requires "geo terminology" to be defined with agreed-upon definitions by members of the ASTM Committee D35 on Geosynthetics. Although D35s primary responsibility is to develop good applicable standards for geosynthetic materials, the committee is aware that numerous geosynthetic terms and their definitions have significant use beyond ASTM. The term geomembrane is the best example of how some geo terminology has found acceptance outside the geosynthetic field and its usage is so engrained that revising its definition is almost impossible. The D35 committee believes the methodology of the terms within ISO Standard 10318, "Geosynthetics - Terms and Definitions", may allow for more flexibility for the future development of appropriate terminology within AS, TM standards. Conversion of ASTM geosynthetic standards to the ISO 10318 terminology will also bring about greater harmonization of standards and terminology throughout the global geosynthetic field.The ASTM Committee D35 on Geosynthetics will start the process of converting D35 geosynthetic standards to ISO terminology at its Jan. 29-31,2014, meetings in Houston, Texas. This process will start with the revision of standards that have the term geomembrane within them. The procedure for this conversion so far has not been determined and will be discussed further within the D35.93 terminology sub-committee meeting, Friday, Jan. 31, 8-9 a.m. The D35 committee seeks input and assistance from interested parties on how to proceed with this conversion process. For more information about the January 2014 ASTM meeting or other geosynthetic terminology conversion issues, please contact: Robert Lozano, chairman, ASTM D35.93 Subcommittee on Terminology, lozanoreng@aol.com., Katerina Koperna, ASTM D35 staff manager, kkoperna@astm.org.; Bob Mackey, chairman, ASTM Committee D35 on Geosynthetics, £bmackey@s2li.com.