anchor.diff:  : UJ, ( addr rd opmask -- )
   	4 ALIGN (rd)
   	>R LC WORD+ - R>
  -	OVER $100000 AND 11 LSHIFT OR
  -	OVER $0007FE AND 20 LSHIFT OR
  -	OVER $000800 AND 9 LSHIFT OR
  -	SWAP $0FF000 AND OR W, ;
  -
  +	S>UJ W, ;
   
   \ Label Management.  Words of the form X> construct relocation records for
   \ as-yet-undefined symbols.  The different forms of relocation records exist
  
positive.code: 	lookup 0= ABORT" Label not defined"
  	DUP >BODY @ ['] val = NOT ABORT" Label expected"
  	EXECUTE gp0 @ - ;
  
  	\ Apply a single fix-up.
  : fixup ( fx -- )
  
negative.code: : lookup ( -- xt f )
  	BL WORD FIND ;
  
  	\ Handle a generic forward reference.
  : (>) ( xt -- : "word" )
  	>IN @
  	lookup IF
  		>BODY
  