The American National Standards Institute has approved ANSI/SCTE 54 2015, "Digital Video Service Multiplex and Transport System Standard for Cable Television." The document describes the transport subsystem characteristics and normative specifications of the in-band service multiplex and transport subsystem standard for cable video.
The standard is available at http://www.scte.org/SCTE/Standards/Download/SCTE/Standards/Download_SCTE_Standards.aspx.