What follows is an opinion from a United States Court of Appeals.
Intervenors who participated as parties at the courts of appeals should be counted as either appellants or respondents when it can be determined whose position they supported. For example, if there were two plaintiffs who lost in district court, appealed, and were joined by four intervenors who also asked the court of appeals to reverse the district court, the number of appellants should be coded as six.
When coding the detailed nature of participants, use your personal knowledge about the participants, if you are completely confident of the accuracy of your knowledge, even if the specific information is not in the opinion. For example, if "IBM" is listed as the appellant it could be classified as "clearly national or international in scope" even if the opinion did not indicate the scope of the business. 

Your task concerns the first listed appellant. The nature of this litigant falls into the category "private organization or association", specifically "business, trade, professional, or union (BTPU)". Your task is to determine what subcategory of private association best describes this litigant.

Opinion:
DI MAGGIO v. ELASTIC STOP NUT CORPORATION OF AMERICA (INTERNATIONAL UNION, UNITED AUTOMOBILE, AIRCRAFT AND AGRICULTURAL WORKERS OF AMERICA, C.I.O., LOCAL NO. 726, Intervener).
No. 9271.
Circuit Court of Appeals, Third Circuit.
Argued Feb. 7, 1947.
Decided May 20, 1947.
McLAUGHLIN, Circuit Judge, dissenting.
Abraham L. Friedman, of Newark, N. J. (Rothbard, Harrb & Oxfeld, Samuel L. Rothbard, and Emil Oxfeld, all of Newark, N. J., on the brief), for appellant.
Edw. V. Ryan, Asst. U. S. Atty., of Newark N. J. (Edgar H. Rossbaeh, U. S. Atty., of Newark, N. J., on the brief), for appel-lee.
Hamilton Hicks, of New York City, and Whittemore, Porter & Pollis, of Elizabeth, N. J. (Phidias L. Pollis, of Elizabeth, N. J., and Frederic P. Weller, of New York City, on the brief), for respondent.
Before BIGGS, GOODRICH, and Mc-LAUGHLIN, Circuit Judges.
GOODRICH, Circuit Judge.
This case presents the same general question as that involved in the Gauweiler and Koury litigations, 3 Cir., 162 F.2d 448, decided this day. The facts may be briefly summarized and from, this summary the relevancy of the rule announced in the two decisions just mentioned will be apparent.
Petitioner was first employed by the respondent on June 9, 1941. On April 30, 1943 he was inducted into the army. The job he left was the job of set-up man in the counter-sinking and hand tapping department. On June 19, 1944, employer and union entered into a bargaining agreement by which certain union officers had top seniority. This is the same agreement mentioned in the Gauweiler and Koury cases. Di Maggio was honorably discharged December 10, 1945, and subsequently went back into the company’s employ to work in his former position. In putting Di Maggio to work as a set-up man his employer displaced an employee named Yorke who was a section steward and who, under the contract, had seniority over Di Maggio. The union brought the matter of Yorkc’s rights under the contract to arbitration as provided for in the labor agreement and ihe arbitrator’s award was that York was entitled to rcinstatment with back pay. The company obeyed the order of the arbitrator and found other work for Di Maggio.
Like Koury, Di Maggio joined the union following his return from service and, again like Koury, filed his petition a few days after the consummation of the 1946 contract between union and employer on June 13, 1946. It is to be noted that Di Maggio does not complain that he was either discharged or laid off. Like Koury, his claim is to be restored to his former position with payment for the difference between the pay carried by that position and that given him by the other jobs to which he has been assigned since his return. The District Court awarded him the relief prayed for.
What we have said in the Gauweiler and Koury cases disposes of the present litigation without further discussion. There is the additional fact to be noted here that it appears both in the pleading and by the testimony that there were, at the time of the litigation, other employees of fhe company with seniority, by actual length of service, greater than that of Di Maggio. In that event it is quite clear that Di Maggio was not entitled to displace such employees because, even at the time of this litigation, it had been made clear that the veteran docs not per se become entitled to super seniority. And this situation, we think, shows again that the solution to the problem given in the Gauweiler case is the one which will bring the matter out with fairness to the veteran and avoid confusion to the employer. If the respondent must pay Di Maggio on the basis of the wages attached to his former position from the time of his return, must it not, also, under its contract, pay the same wages to the other employees who out-rank Di Maggio in seniority? It has already been compelled to do so with regard to the union section steward and we see no escape for it under the contract so far as others senior to Di Maggio are concerned. This, we think, is very hard on the employer as well as an interference with the usual process of collective bargaining and a source of confusion as to the rights of one veteran over another.
The judgment is reversed and the case is remanded to the District Court for proceedings not inconsistent with this opinion.

Question: This question concerns the first listed appellant. The nature of this litigant falls into the category "private organization or association", specifically "business, trade, professional, or union (BTPU)". What subcategory of private association best describes this litigant?

Choices:
Business or trade association
utilities co-ops
Professional association - other than law or medicine
Legal professional association
Medical professional association
AFL-CIO union (private)
Other private union
Private Union - unable to determine whether in AFL-CIO
Public employee union- in AFL-CIO (include groups called professional organizations if their role includes bargaining over wages and work conditions)
Public Employee Union - not in AFL-CIO
Public Employee Union - unable to determine if in AFL-CIO
Union pension fund; other union funds (e.g., vacation funds)
Other
Unclear

Answer: 5