This is in reply to your 12/04 post Altar saints in Seal 5 versus those come out from great tribulation in Revelation 7 (fivedoves.com)  As I see it, the souls seen under the altar in heaven after the 5th seal is open are great tribulation saints who haven't been resurrected yet into an immortal body otherwise why are they called souls under the altar in heaven.  They are given white robes and told to rest for a little season until their fellow servants and brethren should be killed as they were, should be fulfilled. There is a little season between the 5th seal & 6th seal when the rest of the great tribulation saints are killed by being beheaded for not worshipping the image of the beast just like the souls under the altar in heaven were.  The souls under the altar in heaven will be resurrected into an immortal body along with the rest of the great tribulation martyrs after the 6th seal is opened.  They all came out of great tribulation. 

As for the great tribulation saints washing their robes white in the blood of Jesus, it means they all repented, confessed their sins to the Lord and asked for forgiveness for their sins just like all true Christians have since the beginning.  Then the blood of Jesus cleanses them of all unrighteousness and sin which all the saints have had to do through their lives.