This has been a big question on a lot of military forums. One guy wrote:
Trying to list some typical terminology found on DD214's. Once we get all this down, I am going to post all the info and "pin it", so it will be readily available for all to see.
AUS-Army of the United States
ERC-Enlisted Reserve Corp
Reason for Authority for Separation-Rel to ERC SR means Relieved from active duty to Enlisted Reserve Corp. SR means Special Regulation
More to come. Gotta get back to bed and get some sleep... 
My DD-214 don't got the two you mention. rocky
Ok, here`s the official scoop on the shoulder patch from the Army Institute of Heraldry
The Institute of Heraldry Home Page
1st Engineer Brigade Insignia Page
Shoulder Sleeve Insignia
Description: On a blue rectangular background with a rounded top, 3 1/8 inches (7.94 cm) in width and 3 1/4 inches (8.26 cm) in height, a modern anchor palewise behind a sub-machine gun fesswise on which is perched an eagle with wings displayed and inverted all in golden yellow.
Symbolism: The design was based on the design of the British Combined Operations patch which was worn by commandos, landing craft personnel, and others.
Background: The shoulder sleeve insignia was originally approved for the Engineer Amphibian Units on 17 June 1942. It was redesignated for all Army personnel assigned to the following amphibian units: Amphibian Tank Battalions; Amphibian Tractor Battalions; Engineer Amphibian Units; Joint Assault Signal Companies; Headquarters Ships Detachments (Type A); Headquarters Ships Detachment (Type B ); Headquarters Section (Army); and Amphibian Training Command - Pacific Fleet on 10 June 1944. The insignia was redesignated for the 1st Engineer Brigade and amended to update the description and add a symbolism on 20 July 2007. (TIOH Dwg. No. A-1-263)
The shoulder sleeve insignia was originally approved for the Engineer Amphibian Units
That is absolutely correct. It's just a generalized engineer amphibian patch. It is NOT a unit patch.
Many people write to me and say "this was my dad's bn (or regimental) patch." I write and give them the above info. Sorry you still have to dig for their UNIT patch, I explain...
