Work is done to review and define the full set of FITS header keywords used at the NOT. This work is based on the description of "FITS observation files at the NOT" made in 2004. Many upgrades have been done since, and a cross-check with the new FITS standard version 3.0 (2010) and the updated ESO Data Interface Control document version 5 from 2011 was made, while it was also realized that several keywords needed to be added to the list. A first draft of the updated document was circulated some time ago, and a second one will be circulated during the coming weeks. The objective is to complete the document and implement the changes and additions to the keywords in the current semester.