To better define a product to a customer or supplier, Geometric Dimensioning and Tolerancing (GD&T) is often used as a symbolic way of showing specific tolerances on drawings. GD&T is a valuable tool that effectively communicates the design intent to manufacturing and inspection. It is governed by the technical standard ASME Y14.5-2018, published by the American Society of Mechanical Engineers. 
https://training.omnex.com/geometric-dimensioning-tolerancing/gdt-geometric-dimensioning-tolerancing-fundamentals?utm_source=event-promo&utm_medium=townscript&utm_campaign=gdt

This three-day course covers all aspects of GD&T. In additional to presenting the theory, multiple examples will be provided to show specific applications. Participants are welcome to bring sample prints to the class for discussion or private consultation.