The National Labor Relations Board petitions, pursuant to section 10(e) of the National Labor Relations Act, 29 U. S.C. § 160(e) (1964), for enforcement against the respondents, the Food Employers Council, Inc., and the Retail Clerks Union, Local 770, of an order issued on March 15, 1967. The Board’s decision and order are reported at 163 N. L. R. B. No. 58. The Food Employers Council has filed with this court a waiver of its right to submit oral and written argument, and active opposition to enforcement of the order is undertaken only by the Retail Clerks Union.

At issue is the Board’s finding that the respondents committed unfair labor practices when they sought to apply the terms of their collective bargaining agreement to certain employees of the Food Employers Council’s members. The Council is comprised of several employers who operate retail food markets in Southern California. For many years the organization has on behalf of its members negotiated master collective bargaining agreements with various labor organizations; such a contract is the one here in question, made effective by respondents for a five-year term on April 1, 1964. The Board found that by attempting to apply its provisions —one of which was a union-security clause — to snack bar employees of the Council’s members at a time when the Retail Clerks did not represent a majority of such employees, the Council violated section 8(a) (1), (2), and (3) of the Act, 29 U.S.C. § 158 (a) (1), (2), (3) (1964), and the union section 8(b) (1) (A) and (2), 29 U.S.C. § 158 (b) (1) (A), (2) (1964).

The evidence is basically undisputed, and both parties agree that the only question before us concerns the propriety of the Board’s conclusion that the snack bar employees in question “were not an accretion to the existing unit but instead constituted a separate and distinct operation,” and that consequently those employees should be afforded the opportunity to determine for themselves whether they want to be represented by a bargaining agent and, if so, to choose that agent, rather than have such determinations made for them by the Council and the Retail Clerks.

The question of whether a group of employees represents an “accretion” to an existing unit, so that the group is governed by the larger unit’s choice of bargaining representatives, is similar to the issue of a particular unit’s “appropriateness” for purposes of bargaining. See section 9 of the Act, 29 U.S.C. § 159 (1964); Local 620, Allied Industrial Workers of America, AFL-CIO v. NLRB, 375 F.2d 707, 710-711 (6th Cir. 1967). The general outlines of the accretion issue are fairly set out in the Board’s brief:

The trial examiner’s findings relating to this issue — findings supported by substantial evidence and adopted by the Board — are as follows:

On these facts the examiner and the Board concluded that

and that the snack bar employees could not be regarded as an accretion to the existing unit.

The Board’s discretion in drawing the boundaries of “appropriate units” for purposes of bargaining is extremely broad. E. g., Foreman & Clark, Inc. v. NLRB, 215 F.2d 396, 405-406 (9th Cir.), cert. denied, 348 U.S. 887 , 75 S.Ct. 207 , 99 L.Ed. 697 (1954); NLRB v. Schill Steel Prods., Inc., 340 F.2d 568, 573-574 (5th Cir. 1965). We do not endorse all that may be read into the suggestion made in Local 620, Allied Industrial Workers of America, AFL-CIO v. NLRB, 375 F.2d 707, 711 (6th Cir. 1967), that, since “[h]ere the question [is] whether the boundaries of a valid bargaining unit could be contractually extended by an employer and union to cover employees * * * who never indicated their support of that union,” the fact “[t]hat this is not a representation case does not change the role of the Board.” As the Seventh Circuit pointed out in NLRB v. Appleton Elec. Co., 296 F.2d 202, 206 (7th Cir. 1961),

Nevertheless, the Board’s discretion in gauging the proper scope of bargaining units does not completely disappear in cases such as this. In determining whether a group of employees represents an accretion to an existing unit the Board must consider unique and complex sets of facts in light of the somewhat conflicting policies of stability in bargaining relations, see NLRB v. Appleton Elec. Co., supra, and assurance to employees of the right to choose their own bargaining agents, see NLRB v. Masters-Lake Success, Inc., 287 F.2d 35 , 36 (2d Cir. 1961).

It is true that in certain similar factual situations the Board has preferred larger units of the sort contended for here by the union. The Great Atlantic & Pacific Tea Co., 140 N.L.R.B. 1011 (1963); Safeway Stores, Inc., 137 N.L.R.B. 1741 (1962); cf. Priced-Less Discount Foods, Inc., d/b/a Payless, 157 N.L.R.B. 1143 (1966). See also NLRB v. Appleton Elec. Co., 296 F.2d 202 (7th Cir. 1961). In others, however — including cases involving members of the Council — the Board has found more narrowly drawn units to be more appropriate. Piggly Wiggly California Co., 144 N.L.R.B. 708 (1963); cf. The Boy’s Market, Inc., 156 N.L.R.B. 105 (1965), enforced sub nom. Retail Clerks Union, Local 770 v. NLRB, 370 F.2d 205 (9th Cir. 1966). It is not clear that in deciding such cases the Board has been entirely consistent, see Melody Music, Inc. v. FCC, 120 U.S.App.D.C. 241 , 345 F.2d 730 (1965) ; cf. NLRB v. Metropolitan Life Ins. Co., 380 U.S. 438 , 85 S.Ct. 1061 , 13 L.Ed.2d 951 (1965), or that it has not in this case approached the bounds of its discretion. There is in the record considerable evidence that snack bar employees do share a certain “community of interest” with the employees represented by the respondent union. We believe, however, that such evidence, when weighed against that supporting the Board’s conclusion (set out, supra), is insufficient to render that conclusion an abuse of discretion. See NLRB v. Masters-Lake Success, Inc., 287 F.2d 35 (2d Cir. 1961); cf. Local 620, Allied Industrial Workers of America, AFL-CIO v. NLRB, 375 F.2d 707 (6th Cir. 1967).

It would nonetheless be helpful to reviewing Courts of Appeals if future Board decisions of this sort would more carefully analyze the competing considerations involved, including the claims of previous decisions for some precedential value. It is true that “[wjhether or not a particular operation constitutes an accretion or a separate unit turns, of course, on the entire congeries of facts in each case.” The Great Atlantic & Pacific Tea Co., 140 N.L.R.B. 1011 , 1021 (1963). That truth does not, however, preclude the need for rational and reasonably consistent assessments of such factual situations.

We conclude that the Board’s order should be, and it is, ordered to be enforced.

“4. The contract also expressly excludes from its coverage meat department employees and janitorial and maintenance personnel, both of which groups are represented by other unions. . As we suggested earlier, it is not irrelevant that in this case “the issue before us is to determine the lawfulness or unlawfulness of [the respondents’] past conduct,” and not merely “to determine prospective rights and obligations.” NLRB v. Appleton Elec. Co., 296 F.2d 202, 206 (7th Cir. 1961). In situations in which complex and difficult factual determinations are necessary, however, it would seem advisable — and not unduly burdensome — for unions such as the respondent here to resolve close questions concerning the extension of bargaining agreements in favor of proselytizing the employees in question rather than seeking to represent them through the fait accompli of accretion. We frown upon the “successful coup” technique. Cf. Retail Clerks Union, Local 770 v. NLRB, 370 F.2d 205 , 208 (9th Cir. 1966).