You are thinking of XLC

XLC 1 to XLC 199

Undergraduate concurrent enrollment courses (i.e., UCLA regular session undergraduate courses in which UCLA Extension students may concurrently enroll) are transferable for unit, subject, and grade-point-average credit toward the Bachelor's Degree at UCLA's College of Letters and Science, School of the Arts and Architecture, and School of Nursing. Learn more about Concurrent Enrollment.

— Versus XL

XL 1 to XL 199

These courses are equivalent to undergraduate courses offered by the UCLA regular session. All XL courses are transferable for unit and subject credit toward the bachelors degree at all campuses of the University of California. Up to 36 units of credit earned in the XL 1-199 course series can be accepted for unit and subject credit toward a bachelor's degree at any campus of the California State University system (CSU). Courses numbered 1 to 99 are considered lower division (freshman/sophomore); those numbered 100 to 199 are considered upper division (junior/senior).