The phrase "a core functionality of" is correct and usable in written English.
It can be used when discussing the essential features or capabilities of a system, product, or service.
Example: "The ability to process data in real-time is a core functionality of this software."
Alternatives: "a fundamental feature of" or "an essential capability of".
Css, cascading style sheets, a core functionality of front-end development, the styles that lay out the page and give it both its unique visual flair and a clear, user-friendly view to allow readers, who never linger on pages we would like to think they do, some help to read or skim the contents quickly.
In addition, CoAP provides optional transport reliability, normally a core functionality of TCP, which is due to the resource constraints by nature not available in wireless sensor networks (WSNs).
Apple bet on an extremely important core functionality of its device, and I hope it's worth it.
Slacker's player shares a lot of the core functionality of MyStrands and Last .fm
If that sounds a lot like the core functionality of the likes of Readability or Instapaper, you're probably thinking in the right direction.
"The core functionality of a smart city requires a vast amount data to be collected on every aspect of our lives every minute of every day.
Pre-emptively dubbed the "Steam Box" by the gaming community, the technology was expected to be a dedicated machine focused upon Steam functionality and maintaining the core functionality of a traditional video game console.
It really does make sense for the operating system to include all the core functionality of a Web browser: making connections across the Internet, interpreting the HTML code in which Web pages are written, displaying the results in a window.
According to Taylor, it's also just a matter of making the core functionality of document creation more useful.
