| Frequently parts have
repetitive patterns of features. Often it is desirable to use
one of the features as a datum feature and control the other
features in the pattern relative to that datum. On the part
shown the 6X Ø8 holes are located from datums A, B and C. A
very cumbersome way to locate the 2X Ø4 patterns of holes
relative to the Ø8 holes individually, would be to assign a
different letter to each of the Ø8 holes exhausting six
letters of the alphabet. This awkward method is shown in the
first drawing. A more efficient approach is illustrated on the
second drawing. The Ø8 holes are identified as datum feature D
INDIVIDUALLY. Each pair of Ø4 holes has a position callout
relative to A, D, B where D is the large hole nearest each
pair. There are actually 6 datum D features. By using the
INDIVIDUALLY note, the drawing is greatly simplified.
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