NuSDaS definition file is a plain text file that describes structure of NuSDaS dataset. The definition file looks like free format. More precisely, the file is interpreted line by line. Each line is broken down to words by spaces (ASCII SPC). Note that TAB character is not allowed in the definition file. A line starting with keyword (listed below, case insensitive) starts statement. Following lines without keyword at the top of themselves are continued lines and interpreted as one statement with starting line. A line that begins with number sign ('#', also known as sharp, pound, or igeta) is a comment line and will be safely ignored.
Statements can be omitted, unless noted 'mandatory'. There is a limitation in order of the statements. Since they are not (and cannot be easily) documented, the author recommends to describe statements in order of following description.