각각 data type 이 변할때 마다 , structure  include 될때마다

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In the sample structure below that contains three fields, no alignments are created in an NUS or US.

BEGIN OF struc1,
  a(1) TYPE X,
  b(1) TYPE X,
  c(6) TYPE C,
END OF struc1.

In the next example, however, alignments are created in a US but not in an NUS. The first alignment gap is created because of the alignment of structure struc3, the second because of the alignment of C field c, and the third because of the addressing of integer d.

BEGIN OF struc2,
  a(1) TYPE X,
  BEGIN OF struc3,
    b(1) TYPE X,
    c(6) TYPE C,
  END OF struc3,
  d TYPE I,
END OF struc2.