US financial institutions are prohibited from making Iranian loans or providing credits. Foreign exchange transactions, subject to US jurisdiction, are barred.
Transfers of credit or payments between or through financial institutions, subject to US jurisdiction, are prohibited.
Property and interests in property in America are blocked. They may not be "transferred, paid, exported, withdrawn, or otherwise dealt in." Foreign branches are included.
Americans are prohibited from "investing in or purchasing significant amounts of equity or debt instruments of a sanctioned person."
Goods, technology, and services may not be imported into America directly or indirectly.
Property and interests in property in America are blocked. They may not be "transferred, paid, exported, withdrawn, or otherwise dealt in."
Overall, congressional sanctions and Obama's EO prohibit companies and individuals from doing business with Iran's oil, petroleum products, natural gas, and petrochemicals industries.
Prohibitions target companies involved in mining uranium with Iran; selling, leasing or providing oil tanker services; offering insurance to the National Iranian Tanker Company; or engaging in any other financial services.
http://rense.com/general95/sanctionsgame.html