CFR › Title 40 › Part 63 › §63.340 CFR §63.3Verified against eCFR.gov as of June 20, 2026View official text on eCFR.gov ↗Copy linkUsed in this part are abbreviations and symbols of units of measure. These are defined as follows:(a)System International (SI) units of measure:(b)Other units of measure:(c)Miscellaneous: