The image below shows part of the list of equities whose options trade on the CBOE (link). I understand the first three columns (DPM in the third column stands for "Designated Primary Market-Maker"). But what does the last column, "POST/STATION", mean? What is a "post/station"? Why do some entries have it and others don't?
I also noticed that all entries with a DPM have a "post/station", but not all entries with a "post/station" have a DPM. Why is that?
CBOE is one of the few exchanges that still has a trading floor (the options exchanges began to go electronic in 2000) and CBOE themselves went electronic in 2006 with their "Hybrid" trading system, combining electronic and floor trading.
The posts are remnants of the physical trading floor, where a market maker would stand at his 'post' or booth and floor brokers would walk over to the market maker's booth to buy and sell options. However the floor activity is minimal so some firms don't maintain a floor presence. Many firms (including DPMs) only trade electronically.
When I was last at the CBOE trading floor, there was only any significant activity in the SPX options pit and the VIX pit (called "the library" as it is so quiet compared to the SPX pit). SPX options are still exclusively floor traded.
