Cash items refer to various payment vouchers expressed in foreign currency that can be circulated and transferred in the international market and freely converted into other countries' currencies. The currencies of major western countries, such as US dollar, British pound, Swiss franc and German mark, are widely used in international settlement. The countries that issue these currencies have loose foreign exchange control and control, and some even basically cancel foreign exchange control, while some countries have strict foreign exchange control, so their currencies cannot be freely converted into internationally used foreign currencies.

Investment projects refer to activities and policies planned and implemented to achieve a certain development goal (or a group of development goals) in a certain period of time. All investments in an investment project are closely related, and technology and economy are intrinsically linked. In management, it is necessary to make planning decisions, raise funds and organize implementation in a unit, and an investment project must also maintain certain independence from other investments.