C C89509 NCPDP StrengthUnitOfMeasure Terminology C28253 Milligram Milligram A metric unit of mass equal to one thousandth of a gram or 1000 micrograms. One milligram equals approximately 0.015 432 grain or 35.274 x 10E-6 ounce. C C89510 NCPDP QuantityUnitOfMeasure Terminology C28253 Milligram Milligram A metric unit of mass equal to one thousandth of a gram or 1000 micrograms. One milligram equals approximately 0.015 432 grain or 35.274 x 10E-6 ounce. C C89508 NCPDP StrengthForm Terminology C62653 Pack Pack Dosage Form A number of individual items packaged as a unit.