SITC Ori    SITC Rev.1    SITC Rev.2    SITC Rev.3

          Year of revision                    1950        1960          1975          1985

Number of articles in Sections (column 1)       10          10            10            10
Number of articles in Divisions(column 2)       52          56            63            67
Number of articles in Groups   (column 3)      150         177           233           261
Number of articles in Subgroups(column 4)       �\         625           786         1,033
Number of articles in Items    (column 5)      570       1,312         1,832         3,121