Can someone please explain this struct?
<p>Can someone please explain what the meaning of this code? I know somehow the first two bytes represent the underlying id, the next byte represents exchange id etc but I am wondering how exactly does the :16, :8 work. Any references will be helpful and I couldn't really find any documentation on this. Thanks</p>

<pre><code>    struct ParamFieldIndex
    {
        uint64_t _uid_or_term:16; // udl_id
        uint64_t _exch:8; // exchange id
        uint64_t _oid_expid:32; // expid or oid
        uint64_t _fid:8; // field id
    } AMM_PACKED;
</code></pre>
