What does the letter (like E in our case) mean at the end of the standard like ISO/IEC 17020:1998
(E)?
"E" stands for English. When you get English version, it will be with the suffix E.
Refer to this weblink -
http://www.iso.org/iso/en/catsupport/howcat.html?scopelist=CATALOGUE
Languages - The official languages of ISO are English, French and Russian. ISO International Standards and standards-type documents are usually published by the Central Secretariat in separate English and French editions. Some standards are also published in an additional language edition, while other standards in certain fields, most notably in the field of information technology, are frequently published in English only. Certain standards, especially in the field of terminology, are published in bilingual (English, French), trilingual (English, French, Russian) or quadrilingual (English, French, Russian, German) editions. A few ISO standards are also published in Russian and in Spanish. Information pertinent to each standard is indicated in its bibliographic data.