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The STRING structure contains the length, the maximum length, and a pointer to a buffer containing the string.

 typedef struct _STRING {
   USHORT Length;
   USHORT MaximumLength;
   [size_is(MaximumLength), length_is(Length)] 
     CHAR * Buffer;
 } STRING,
  *PSTRING;

Length: The length of the data pointed to by Buffer, in bytes.

MaximumLength: The total allocated length of the data pointed to by Buffer, in bytes.<6>

Buffer: A pointer to a buffer containing the character string.