Hi Pavel,
Thanks for the pointer. It did help me some and I'm sure it will be useful in the future, but I don't think I asked the right question. For example, using the <ctrl>click approach, I did locate the code:
/*! @brief CDC ACM instance count */
#ifndef USB_DEVICE_CONFIG_CDC_ACM
#define USB_DEVICE_CONFIG_CDC_ACM (0U)
#endif
in the usb_device_config.h file.
However, my question should have been: Where in the "Manage SDK Components" menu system can I turn this on? In the "Middleware->USB" section, I did select "USB Device->USB Device CDC" and noted that other selections became active. But the code I was looking for is still not active as USB_DEVICE_CONFIG_CDC_ACM now has a value of 0.
I am trying my best to work within the framework that MCUXpresso provides and have all of my edits in the "source" directory. It's all part of the learning process.
Thanks, Dave