Counters (
http://asciidoctor.org/docs/user-manual/#counters) cause unnecessary confusion through not being fully fledged attributes. They look like attributes, but they have more restrictive names, cannot be accessed reliably, and have a different syntax for setting.
It would be cleaner to do away with counters and replace them with an operation that worked on any attribute:
{increment:part_number}
which means increment then display the attribute "part_number".
Users already know how to name, set, and access attributes so this would be much easier to remember.
If there was a demand for an equivalent to counter2: it could be {increment_noshow:part_number} although I don't think it is needed.
At the same time, the definition of "increment" could be made more intelligent by detecting and incrementing a terminal sequence of digits instead of just the last character, ie
:part_number: PX-021
{increment:part_number}
returns PX-022
Locked
