The 12-hour clock is a time convention in which the 24 hours of the day are divided into two periods: a.m. (from the Latin ante meridiem, meaning "before midday") and p.m. (post meridiem, "after midday"). Each period consists of 12 hours numbered: 12 (acting as zero), 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, and 11.
The 12-hour clock was developed over time from the mid-second millennium BC to the 16th century AD.
Road Dog Trucking is a trucker's talk radio channel on the Sirius XM Radio service. The subjects cover those relevant to the trucking community, be it politics, economics, or social issues. On 2009-02-17, the Sirius channel's programming merged with the programs heard on XM Radio's Open Road. Most of the programs from both services were retained.
In 2003, Sirius launched its dedicated truckers channel Sirius Trucking Network. It retained the name until March 2006, when the channel was renamed to Road Dog Trucking.