Encoded Engrams (White Engrams) are Common Engrams dropped by defeated enemies or purchased from Cryptarch. There are 9 weapon Encoded Engrams, one for each type of weapon. There are 7 Armor Encoded Engrams, one for each armor slot and another 3 for the bonds, marks and capes.
Most of the time Encoded Engram will decrypt into a Common item. Occasionally you can find a Uncommon (green) item from it.