ASME Y14.38-2007 (R2013)

The intent of this Standard is to allow the use of approved abbreviations in lieu of the use of complete words or terminology. Abbreviations defined by this Standard need not be additionally defined by the using drawing or related document. It is not the intent of this Standard to include abbreviations defined or established in other standards such as those for scientific terms and notations. However, an exception is made for those abbreviations that have widespread use and recognition, for example, AM for amplitude modulation, and FM for frequency modulation (radio).