However, for the most part, very few of these networks have been able to gain a national reach on parity with many of the conventional commercial and non-commercial networks, in part due to the fact that many stations transmit high definition programming on their main feed in 1080i, which requires a bitrate less compartmentalized for allowing more than one multicast feed (which are generally transmitted in standard definition) without risking diminished picture quality; some alternately transmit their main feed in 720p, which favors multiplexing of more than two subchannels at a time (ATSC 3.0, which began development around the time of the 2009 transition with FCC consideration to replace the current ATSC 1.0 as the technological standard for digital television expected to occur in 2016, utilizes improved compression technology able to fit additional subchannels on a single programming stream as well as allowing for the transmission of high definition content in the 4K resolution format).