ABBREVIATIONS AND SYMBOLS

  The following abbreviations and symbols are used in this publication:

 -      Represents zero.
(D)     Withheld to avoid disclosing data for individual companies; data
         are included in higher level totals.
(NA)    Not available.
(NC)    Not comparable.
(S)     Withheld because estimate did not meet publication standards.
(X)     Not applicable.
(Z)     Less than half the unit shown.
n.e.c.  Not elsewhere classified.
n.s.k.  Not specified by kind.
r       Revised.
SIC     Standard Industrial Classification.

Other abbreviations, such as lb, gal, yd, and bbl, are used in the
customary sense.