This array of occupational or trade types was scarcely more extensive than that of the structural types here grouped together. Of these there were the following types. (1) the simple industrial union, wherein all workers engaged, in whatsoever capacity, in any particular industry are members of the same union. This type was represented by the Western Federation of Miners[99]--really the strongest taproot of the I. W. W. (2) The multi-industrial type, a federation of industrial unions, such as the American Labor Union, which included railway employees, engineers, and musicians. (3) The so-called "international" union, rarely more than national in scope, and merely a national association of local unions of a given trade. This type was represented by the United Metal Workers International Union of America. (4) The non-federative industrial union, like the United Mine Workers of America with industrial rather than trade units, an industrial organization which excludes federation with similar organizations in other industries, or with employers. (5) The ordinary non-federative trade unions, here seen in two types: (_a_) the trade amalgamation, a federation of unions wherein the constituent bodies are so united as to preserve their individuality, although trade autonomy is thereby destroyed. This type is illustrated here by the Amalgamated Society of Engineers; (_b_) national unions of any particular trade like the iron molders, wherein the constituent unions are more subordinated to the national body than in the amalgamation. (6) The state federation--as typified by the Utah State Federation of Labor. And finally (7) the rather unconventional type of "union," represented by the Industrial Workers' clubs and the United Labor League. It should be understood that but a small part of the "international" or national bodies was represented as a whole. The greater number were represented by one or two locals. A number of them were affiliated with the American Federation of Labor at the time, but had become dissatisfied with the policies of that body.[100] However, some of the unions most prominent in the activities of the convention were represented as central or national bodies with all their constituent local unions. Such were the American Labor Union and the United Metal Workers.