Blizzard removed the Shadow Dance (aforementioned SD) Stance for the Rogue in the 7.0 update of World of Warcraft. It has two major issues : the main bar no longer switches from the normal to the stealth bar when the ability is activated, and since the SD Stance no longer exists it can't be used as a conditional for macros.

There are a lot of threads on the WoW's official and community forums about how this change is bad, and should be reverted as a lot of rogues just doesn't want to play Subtlety anymore. Blizzard almost ignored the requests made from the players, first for the Legion Alpha and when the 7.0 patch came out two weeks ago.

Here is a list of quotes explaining why this should be reverted, coming from this offical forums thread :

• Without the shadow dance bar, the stealth bar is completely useless for sub rogues, because anything you bind there you have to bind elsewhere or you wont be able to use it in Shadow Dance.
  [...]
  It creates ADDED button clutter, and makes it more difficult to pull off signature rogue skill moves like vanish sap etc.
• Either fix shadow dance, or remove the stealth bar. Because not having SD activate it makes the stealth bar an unusable UI inconvenience.
• I have Backstab bound to 1 and I have Shadowstrike bound to the ~ key. Currently, to build CPs I spam away at '1' then dump them with a finisher. Great, feels good to use. Then it's time to Shadow Dance. I hit that but now i have to spam ~. Now I know people keep saying "it's just one different keybind. How hard is it to press". That's the thing though, it's not hard. It just makes it feel clunky to me. You get into a rhythm and then activating Shadow Dance breaks that rhythm.
• I started leveling a rogue recently for the first time cuz I wanted to use it for PvP. I bounced around between all the specs for the first 20 levels before settling on Sub as my favorite. I played it for the next few levels until I hit 36 and unlocked shadow dance. All of a sudden my nice neat bars of stealth and non-stealth abilities have to be completely upended because the paging is messed up arbitrarily.

Here is a list of forums threads complaining about this change and discussing about it :

http://us.battle.net/forums/en/wow/topic/20747714932
http://us.battle.net/wow/en/forum/topic/20747714800
http://us.battle.net/wow/en/forum/topic/20745324658
http://us.battle.net/wow/en/forum/topic/20747615017
http://us.battle.net/wow/en/forum/topic/20747804902
http://us.battle.net/forums/en/wow/topic/20743726122 (you'll need to dive a little)
http://us.battle.net/forums/en/wow/topic/20746954787
http://www.mmo-champion.com/threads/2012478-Legion-shadowdance-bar-(macro-addon-)
http://www.wowinterface.com/forums/showthread.php?t=53473