Minarettes

 Early this year I bought a couple of containerised minarette apple plants -
Queen Cox and Ambassy/Winter Gem - and they are doing well planted two foot
square six inch high raised beds in a bark covered part of my front garden.
The beds are "mulched" with pea gravel - looks quite good.

The garden centre gave me a booklet entitled  "Fruit Growers Handbook" which
tells when and how to prune.  However, althought the booklet shows diagrams
of minarettes and details the plants' central leaders, laterals and
sub-laterals, its instructions tell one to cut laterals to three leaves,
about 4 inches and sub-laterals to one leaf above a basal cluster.

My question is, "What is a basal cluster?" for the booklet does not say.

Regards

Geoff