text: **Note:**If the entire grain is to be modified and not only part of it (some blocks only), the 
  copy on demand is bypassed. The bitmap is updated, and the grain on the target is 
  modified but not copied first. 
  
  (cid:2) If the bitmap indicates the grain to be modified on the target was copied, it is directly 
  
  changed. The bitmap is*not*updated, and the grain is modified on the target with the new 
  value, as shown in Figure 11-8. 