SEVERE ERROR WHILE CHECKING INPUT SPECIFICATIONS
BLOCK NAME: A MODEL NAME: MULTIFRAC
IF A SIDE PRODUCT IS A TOTAL DRAWOFF FROM A STAGE, THE FOLLOWING
"COL-SPECS" COMBINATIONS ARE NOT ALLOWED: (D,Q1), (D,L1), (D,RR)
AND (B,QN). ERROR ENCOUNTERED IN "COL= 1". PLEASE CHOOSE
ONE OF THE FOLLOWING: (D,QN), (B,Q1) OR (Q1,QN).
这个严重错误怎么解释?