This is already clear in the text, as the following clearly specifies the behavior when ref_pic_list_modification_flag_l0 == 0 and num_ref_idx_l0_active_minus1 >= NumPocTotalCurr (and there is a similar process for list 1):

The variable NumRpsCurrTempList0 is set equal to Max( num_ref_idx_l0_active_minus1 + 1, NumPocTotalCurr ) and the list RefPicListTemp0 is constructed as follows:

rIdx = 0
while( rIdx < NumRpsCurrTempList0 ) {

for( i = 0; i < NumPocStCurrBefore && rIdx < NumRpsCurrTempList0; rIdx++, i++ )

RefPicListTemp0[ rIdx ] = RefPicSetStCurrBefore[ i ]

for( i = 0; i < NumPocStCurrAfter && rIdx < NumRpsCurrTempList0; rIdx++, i++ )

RefPicListTemp0[ rIdx ] = RefPicSetStCurrAfter[ i ]

for( i = 0; i < NumPocLtCurr && rIdx < NumRpsCurrTempList0; rIdx++, i++ )

RefPicListTemp0[ rIdx ] = RefPicSetLtCurr[ i ]

}

Thanks for the comment, you are quite right and this ticket can be marked as invalid.

In my reading I hadn't spotted that there was a while loop before the for loops.

Thanks for the help!