Procedures to determine a crystallographic plane:
(1) If the plane passes through the selected origin, either another
parallel plane must be constructed within the unit cell by an
appropriate translation, or a new origin must be established at the
corner of another unit cell.
(2) At this point the crystallographic plane either intersects or
parallels each of the three axes; the length of the planar intercept
for each axis is determined in terms of the lattice parameters a, b,
and c.
(3) The reciprocals of these numbers are taken. A plane that
parallels an axis may be considered to have an infinite intercept,
and, therefore a zero index.
(4) If necessary, these 3 numbers are changed to the set of
smallest integers by multiplication or division by a common factor.
(5) Finally, the integer indices, not separated by commas, are
enclosed within parentheses, thus: (hkl).
