It's useful to explain to laypeople about CBTC systems' ability to assist on PTC-like responsibilities.
In other words:
"The nature of CBTC means adding PTC-like methodologies is software-based features built into CBTC systems in trains."
"Thusly, existing CBTC systems tend to help automate several operations normally handled by PTC."
(or something like that -- it kind of blurs the lines because a system/mechanism and methodology/responsibilities is kind of integrated in today's software-driven electronics world. For the non-tech person, imagine apps (software) on an iPhone (system). Here, it is metaphorically like "ATC" and/or "PTC" are apps/features included in a "CBTC powered system". A gross oversimplification, but the easiest one-sentence simplification for laypeople)
Right?
(For other readers, the acronym Pandora Box is opened in 2015 thread: New GO Train Control+Signalling (PTC, CBTC, ETC) -- Safety & Subway-Like Frequency)