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  ENUM: ADTableStopCondition
 
   Specifies the stop condition for the last logical AD in this
   table.
 
   For example, the ADTable may have 10 entries, but the second
   entry is a terminating AD (an ad with an extent length of zero).
   In this case, the logical stop condition is ad_Terminating.
   Likewise, a stop may be an ad_Continuation reference to an AED.
   
   If there are no stop conditions (ad_Nonstop), then all ADs in
   this ADTable refer to extents in a logical chain.
 
  DEFINITIONS:
   
   ad_Nonstop       There are no logical stop conditions in the table.
   ad_Terminating   We logically stop on a terminating AD.
   ad_Continuation  We logically stop on a reference to an AED.
 
  ABUSES:
 
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enum ADTableStopCondition {
    ad_Nonstop      = 0,
    ad_Terminating  = 1,
    ad_Continuation = 2
};