- Overview
    . 
- The 6top Sublayer
    . role:
        . [remove?] The current document does not define how flows with multiple priorities are supported. Future extensions to this document might add support for multiple priorities.
        . maintaining (basic) cell usage statistics
        . monitoring and moving (soft) cells
        . there is Objective Function (OF) that takes care of:
            . maintains some statictics as needed
            . maintaining the bandwidth, even when the PDR of the link to a neighbor changes. This might include detecting cells which suffer from collision, and relocating them to a dfferent slotoffset/channeloffset location in the schedule.
            . increasing/decreasing the bandwidth according to the application needs.
    . protocol to add/remove cells to a neighbor. The OF uses this mechanism.
    . a mechanisms by which a neighbor node discovers the OF currently in use by the 6top sublayer (OCP ID or something like that -- see RPL DIO OCP RFC6550).
- Hard/Soft Cells
    . IEEE802.15.4e defines some flags
    . 6top adds additional qualifiers of a cell (NOT strictly speaking flags)
    . soft cells: 6top Monitoring Process active on the cell, the 6top OF is allowed to relocate it
    . hard cells: 6top Monitoring Process NOT active, r/o mode. Exact useage not defined, left open for future use.
    hard cells can only be read
- 6top-to-6top Communication Protocol
    . based on IEs
    . TODO: coordinate with IETF to allocate IE numbering space
    . discovery
- Example Scenarios
- IANA