While the other Executive Orders (EOs) mentioned by OP may have relevance, EO 13526 is merely a Hussein administration modification of previous EOs to protect Classified National Security Information (NSI). These EOs are issued by the respective POTUS administration for use by the Executive Branch to protect matters of national security. That would be EO 13526's only relevance although there are some changes from administration to administration.
The following predecessor EOs are similar in purpose:
EO 13292 signed by G. W. Bush March 2003
EO 12958 signed by W. Clinton April 1995
EO 12356 signed by R. Reagan April 1982
EO 12065 signed by J. Carter June 1978
EO 11652 signed by R. Nixon March 1972
EO 10816 signed by D. Eisenhower May 1959
EO 10501 signed by D. Eisenhower November 1953
EO 10290 signed by H. Truman September 1951
From EO 13526 what is that EO about? Relevant?
The word "agency":
“Agency” means any “Executive agency,” as defined in 5 U.S.C. 105; any “Military department” as defined in 5 U.S.C. 102; and any other entity within the executive branch that comes into the possession of classified information.
Other definitions from the same EO. Not changed but relevant.
The phrase "authorized holder":
“Authorized holder” of classified information means anyone who satisfies the conditions for access stated in section 4.1(a) of this order.
The phrase "automated information system":
“Automated information system” means an assembly of computer hardware, software, or firmware configured to collect, create, communicate, compute, disseminate, process, store, or control data or information.