Already explained by Vinay Sir in the faq.
One shot from me.
1) Start-Intermediate Quota.
2) A constituent of the Remote Quota group. In this case, takes place when the intermediate station does not...
more... have a share of the quota from the originating station; i.e. GNWL. Thus making the relative quota small.
3) Confirmed tickets are issued from GNWL. For combined tickets (Having more than one people in a PNR), confirmed berths can also be given from Pooled Quota. (Depends on availability).
After the confirmed berths are exhausted, most of the times it directly moves to WL.
4) Moves slowly, supports RAC. Becomes handy when the train do not support PQWL.
5) To avoid landing up in RSWL, always check for stations beyond your preferred destination station supporting GNWL.
6) RSWL is usually RLWL. Most of the times RLWL is not visible due to distance restriction and/or restricted booking/s.
7) A train can support more than one RSWL.