which a substitution is to be made can also be indicated directly in the object code the block structure is then dispensed with another option of interest is to specify the name and the symbol reference directly at the end of a block with the symbol reference then being resolved each time after conversion on the card to the actual physical addresses the header 10 then contains a list of the absolute addresses in the order in which they need to be incorporated into the object code there is no need to replace the header for this purpose it is sufficient for an appropriate list to be held in the memory this list can be erased after loading which saves a considerable amount of memory space after this address table or address list has been produced in each case the beginning of a block is read in and the number of bytes which can be read in without converting a symbol reference to the program segment is stored the beginning of the block which of course indicates only the number of bytes in this block is not transferred to the program code at the same time in this context at the end of the block the symbol reference is replaced with the actual current address to this end either the comparison table in the object code header 10 is used or the physical address associated with this block is simply called from an appropriate list in the case of the.