ASTM Metric Units Standard

Title:  IEEE/ASTM SI-10, Standard for Use of the International System of Units (SI): The Modern Metric System

From ASTM International,

This is a voluntary standard for the unified American National Standard for metric units, developed from previous ASTM E 380 and IEEE Std 268. It conforms to latest international standards. For those unfamiliar with SI, this is a valuable reference work.