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--Editor

1. Introduction

In March 2009 the ASME released a new Y14.5 standard, the first since 1994, and there is much in it of great interest and benefit. In order to help potential users decide whether or not to adopt it, we attempt to cast some light on its most important novelties. To set the stage, we start with a definition of GD&T as a whole, in order to be sure we are all on the same page. Next we ask why a new standard might be interesting. Finally, we provide a brief overview of the contents of this evaluation before we go into detail.

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