IEC 60679-3:2012 specifies the outline dimensions and lead connections for quartz crystal controlled oscillators with lead enclosures. This edition includes the following significant technical changes with respect to the previous edition: - CO 01, CO 07, CO 10, CO 17 and CO 18 were deleted; - The current pin layout of CO 06 was deleted. And new pin layout of CO 06 was added as CO 40; - New layout of CO 15 was added as CO 41; - Two new enclosures, CO 42 and CO 43 were added. Therefore revised edition includes 15 types of enclosures as in Table 1 of Clause 5.