A DLC primitive specified in [SP 800-56A] or an RSA Secret Value Encapsulation (RSASVE) operation specified in [NIST SP 800-56B].
Sources:
NIST SP 800-135 Rev. 1
A primitive algorithm used in a key-agreement scheme specified in SP 800-56A or SP 800-56B.
Sources:
NIST SP 800-133 Rev. 2
under Key-agreement primitive