According to the KiCad 5 docs when the three buses PCA[0..15], ADR[0..7] and BUS[5..10] (or BUS[:5..10]?) are connected, it means that the nets PCA5 and ADR5 and BUS5 are connected.
The KiCad 6 docs say:
KiCad 5.0 and earlier allowed the connection of bus wires with different labels together, and would join the members of these buses during netlisting. This behavior has been removed in KiCad 6.0 because it is incompatible with group buses, and also leads to confusing netlists because the name that a given signal will receive is not easily predicted.
If you open a design that made use of this feature in a modern version of KiCad, you will see the Migrate Buses dialog which guides you through updating the schematic so that only one label exists on any given set of bus wires.
So far so good, buses now can’t have more than one label. Or can they?
When I try the above example in KiCad 6, I find that in fact they can have multiple labels and the nets are still connected, but the connection algorithm seems to be different from what was described in the docs. I find that nets are simply matched up in parallel, i.e. PCA0, ADR0 and BUS5` are connected.
Has the behavior not been removed properly and that will be fixed at a later point, or is it just the number-by-number matching that has been removed and multiple labels on a bus are actually still supported?