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:
BROTHERHOOD OF MAINTENANCE OF WAY EMPLOYEES, LODGE 16, et al.; Brotherhood of Maintenance of Way Employees, Grand Lodge, et al., Intervenors, Appellants, v. BURLINGTON NORTHERN RAILROAD COMPANY, Appellee.
Nos. 85-2360, 85-2412.
United States Court of Appeals, Eighth Circuit.
Submitted May 12, 1986.
Decided Oct. 1, 1986.
Harry W. Zanville, Cedar Falls, Iowa, for appellants.
Richard J. Schreiber, Fort Worth, Tex., for appellee.
Before ARNOLD, FAGG and WOLLMAN, Circuit Judges.
PER CURIAM.
This is a suit in equity for an injunction preventing the defendant, Burlington Northern Railroad Co., from putting into effect unilaterally certain methods for detecting drug use among its employees. In general, if a proposed practice by a rail carrier is a clear departure from the collective-bargaining agreement, a dispute over the practice is treated as a “major dispute” under the Railway Labor Act, and the carrier may not proceed without first negotiating with the employees’ representative. But if the proposed practice is arguably justified by the collective-bargaining agreement (including settled past practices of the parties under the agreement), then a dispute is called “minor,” and the carrier may proceed unilaterally, subject to an arbitration process before the National Railroad Adjustment Board.
This appeal involves two disputed proposed practices. First, the railroad wants to administer chemical drug testing to all employees who appear to be involved in any accident or other incident which seemingly stems from human error. Second, the railroad wants to administer similar tests to all employees who return to work after a furlough or similar absence. The District Court, 642 F.Supp. 41, held that the dispute over the first practice (post-incident testing) was minor. It therefore denied the injunction sought against the railroad’s proposed initiation of this practice. But with respect to the second challenged practice (post-furlough testing), the Court held the dispute major and therefore granted the injunction.
Both sides appeal. The union seeks reversal of the denial of the injunction against post-incident testing. The railroad seeks reversal of the grant of the injunction against post-furlough testing.
As to the first issue, we affirm. As to the second, we reverse. The Court’s reasons for these holdings are expressed in two opinions. An opinion by Judge Arnold, in which all Members of the Court join, explains our holding that the railroad may proceed with post-incident testing. An opinion by Judge Fagg, in which Judge Wollman joins, explains our holding that the railroad may proceed with post-furlough testing. Judge Arnold dissents from this latter holding.
The judgment of the District Court, insofar as it denied an injunction with respect to post-incident testing, is affirmed. Insofar as it granted an injunction with respect to post-furlough testing, the judgment is reversed, and the injunction is vacated and set aside.
It is so ordered.

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: 7