I believe you mean CF-8M, which has UNS No. J92900. The ASM Metals Handbook lists both CF-8M and CF-12M as being the nominal cast equivalents of 316SS even though CF-12M has slightly higher C content than CF-8M. It also notes that this is just a nominal equivalent between wrought and cast products. The chemistries of the two metals are not identical. CF-8M has higher Cr, S, and Si values and lower Mn, P, and Ni values than 316SS.
ASTM A743 also lists out the chemical and mechanical properties of CF8M grade of stainless steel. Generally we refer CF8M as a cast equivalent of 316 grade but strictly there are differences in chemistry.