SyndEx is short for "Syndicated Exclusivity". When a TV station in a TV market buys a program to show in that area, they buy the exclusive (as in to exclude anyone else) rights to show that program in that market. Stations pay a premium for this exclusivity.
Dish Network can import a superstation as defined in the law (WWOR, WPIX, WSBK, KTLA, KWGN---no other station is or can be a super station. WGN and WTBS are no longer super stations. WGN has a national channel separate from WGN9 and WTBS no longer exists, it's WPCH now).
The local station has the right to tell Dish Network, "We own this program that is also shown on the super station you are importing. Please block that program in from showing on that station in this TV market."
By law, Dish has to honor that station's request. Dish could just black out the offending program in that market the same way they do sports channels (a completely different story there). However Dish chooses the block the entire channel from being sold in a market if they cannot come to a deal with the local station making the Syndex request.
Dish Network can import a superstation as defined in the law (WWOR, WPIX, WSBK, KTLA, KWGN---no other station is or can be a super station. WGN and WTBS are no longer super stations. WGN has a national channel separate from WGN9 and WTBS no longer exists, it's WPCH now).
The local station has the right to tell Dish Network, "We own this program that is also shown on the super station you are importing. Please block that program in from showing on that station in this TV market."
By law, Dish has to honor that station's request. Dish could just black out the offending program in that market the same way they do sports channels (a completely different story there). However Dish chooses the block the entire channel from being sold in a market if they cannot come to a deal with the local station making the Syndex request.