BS EN ISO 2009:2011

Screws - A simple device use for physically attaching two objects together

Quality - An object that has quality is superior in function and finish than a less quality object.

Dimensions - The shapes and angles of something or a situation.

Head - The upper part of a body typically separated by the neck.

The British Standards Institution are a non profit making organisation, who produce standards and standard related services, for a variety of industries. The standards that they produce are used as a guideline or definition of the minimum levels certain services and product should reach. The standards are produced by BSI directly, following consultations and public enquiries. At shop.bsigroup.com, you can purchase a variety of standards. They stock documents for industries such as food and drink, engineering, building and construction, energy and utilities, transport and agriculture and farming. If you become a member of their site you can get huge discounts on their standards. They also offer training courses and conferences via their website, or you could take advantage of their online standards tools.