What do the temporary designations of asteroid candidates sent from Spacewatch® to the Minor Planet Center's Near-Earth Object Confirmation Page mean?

Key to the designations is given in the table below:

Prefix      Survey Name     COD        Era
------   -----------------  ---  -----------------------

FS-nnn = First Spacewatch®   691  circa 1984-1988)
SS-nnn = Second Spacewatch®  691  circa 1989-2002 Apr 23)
ts-nnn = Third Spacewatch®   291  circa 2001-2011 Oct 1)
SW4xxx =  4th Spacewatch®    691  2002 Apr 24 -present)
SW5xxx =  5th Spacewatch®    291  2011 Oct 16 - present)
SW6xxx =  6th Spacewatch®   ^695  2010 - 2017) using KPNO Mayall 4-meter telescope.
SWBxxx =  Bok Spacewatch®   ^695  2016 Apr 18 - present using Steward Bok 2.3-m telescope.

where "nnn" = an integer from 001 to 999 and "xxx" = a heirarchical
string of characters running sequentially through digits 0-9,
letters a-z (lower-case), followed by A-Z (upper-case).

From 1984 April through 2002 April 23, COD 691 was the Steward
Observatory  0.9-meter f/5 Newtonian telescope with various CCDs
of increasing size with time (also see: 0.9-meter telescope
equipment epoch table).

COD 691 is presently a 0.9-meter f/3 telescope with corrected
prime focus and four CCDs in a mosaic covering an area of 2.9
square degrees (also see: 0.9-meter telescope equipment epoch
table).

COD 291 is the Spacewatch® 1.8-meter telescope with a 2048x2048
CCD at folded, corrected f/2.7 prime focus (also see: 1.8-meter
telescope equipment epoch table).