not to Canada (whose block is CF-CK), but to Chile) and the last letter is "T". Only the third letter varies from market to market; however, that letter is typically the same as the third letter of the CBC Radio One and CBC Radio 2 stations in the same market. An exception to this rule are the CBC North stations in Yellowknife, Whitehorse and Iqaluit, whose call signs begin with "CF" due to their historic association with the CBC's Frontier Coverage Package prior to the advent of microwave and satellite broadcasting. Some stations that broadcast from smaller cities were private affiliates of the CBC, that is, stations which are owned by commercial broadcasters but predominantly incorporated CBC programming within their schedules. Such stations generally followed the CBC schedule, airing a minimum 40 hours per week of network programming. However, they often chose to opt out of some CBC programming in order to air locally produced programs, syndicated series or programs purchased from other broadcasters, such as CTV Two, which do not have a broadcast outlet in the same market. In these cases, the CBC programming being displaced may have been broadcast at a different time than the network, or were not broadcast on the station at all. Most private affiliates generally opted out of CBC's afternoon schedule and Thursday night arts programming. Private affiliates carried the 10 p.m. broadcast of The National as a core part of the CBC schedule, but generally omitted the 11 p.m. repeat (which is no longer broadcast). Most private affiliates produce their own local newscasts for a duration of at least 35 minutes. Some of the private affiliates later began adding CBC's overnight programming to their schedules since the network began broadcasting 24 hours a day in October 2006. Following the disaffiliation of the last privately owned CBC affiliate CKSA-DT in Lloydminster on August 31, 2016, no more private stations operate as CBC affiliates, as many such stations have been purchased either by the CBC itself or by Canwest Global or CHUM Limited, respectively becoming E! (a small system owned by Canwest, but separate from its fully national Global Television Network) or A-Channel (later A, now CTV Two) stations. One private CBC affiliate, CHBC-TV in Kelowna, joined E! (then known as CH) on February 27, 2006. When a private CBC affiliate reaffiliated with another network, the CBC normally added a retransmitter of its nearest O&O