Intermediate? Border Bearded? What are they?

I am so confused when it comes to bearded Iris. If Intermediate Bearded and Border Bearded are both 16 to 26 inches tall, what is the difference? I guess TB start at 27 inches. I can't figgure it out.

TBs do start at 27 1/2 The BBs & intermediates are becoming more like each other, however because of their genetic make-up the borders usually have more buds, & often bloom with the TBs.

One source gives 16" to 27.5" for intermediate , miniature tall and border but other sources
may vary somewhat. Go to www.irisgarden.org/ for a detailed explanation of the differences.

The registration is up to the hybridizer--believe him or her. The groups mentioned in post 6498988 are 3 of the median iris groups, the 4th being standard dwarfs. Height will help people plan their gardens, but is just one part of classification.