The case of the disappearing angle units, or "the dangle of the angle"

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Measurement Good Practice Guide No. 80
Fundamental Good Practice in Dimensional Metrology
David Flack
Engineering Measurement Services Team
Engineering Measurement Division
John Hannaford
First printed July 2005
Reprinted with minor corrections/amendments October 2012
ISSN 1368-6550
National Physical Laboratory
Hampton Road, Teddington, Middlesex, TW11 0LW

"Why are angle units special?
For the measurement of length it is necessary to adopt an ultimate standard, either a material standard such as the former Imperial Standard Yard or a natural standard such as the distance light travels in a certain time. No ultimate standard is required for angular measurement since any angle can be established by appropriate sub-division of the circle."[chapter 2 page 21]

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