cmi5 is an xAPI Profile that bridges the SCORM and xAPI divide by specifying interoperability rules that inform how an LMS and xAPI activities communicate.
The Experience Application Programming Interface (xAPI) is a learning technology specification that enables data encoding, transport, and exchange across a wide variety of activities, experiences, and devices.
It’s here: xAPI is the emerging learning data and analytics specification that will replace—and completely supersede—SCORM in coming years. Also called Experience API, xAPI is an open, industry-wide specification for sending, storing, and retrieving activity about learning and performance experiences.