Abort spellcasting

The ability to abort the casting of a spell is mentioned on B236 under "Time Required":
:You may “abort” an unfinished spell before it is cast, at no penalty, but you must start over if you wish to try again.
The lack of penalty presumably means no energy cost is spent if a spell is aborted prior to casting, the only thing lost would be the time put in.
M5 also lists it under Magical Terms:
:"abort: To stop the casting of a spell before its completion."
==Exception==
Steal Skill on 158 notes a difference:
:The caster may abort his casting at any time; the energy is still spent.
It's unclear in this case when during the minute-long casting time the energy is spent.
==Modification==
The Continuous Ritual perk in Magical Styles also makes reference to this option in normal rules:
:Normally, when you’re done concentrating on a spell, you must either cast it or abort it
and how the perk changes them:
:You can continue to take Concentrate maneuvers for as long as you want, until you cast, abort, or are distracted or incapacitated
category:rules