Fresno Iris Society has used English Box over the years and has not had a problem. There are several choices and so I am attaching the Judges Handbook Rules Chapter 25 for you to see for yourself.
Our show schedule approved by AIS:
SECTION E English Box (Not eligible for Best of Show)
Exhibitors will furnish their own box. Designed as a means of displaying collections of single flowers without stem, foliage or the presence of buds. The entire emphasis is on the beauty of each individual blossom. For This Show: Exhibits will contain 6 individual blooms, all properly labeled in a water box; one classification per box.
1. Same color or pattern 2. Same hybridizer 3. Mixed colors or patterns
Hope this helps,