collective packaging is a new type of packaging developed in the 1950s. It is a new development of modern transportation packaging and occupies a very important position in contemporary commodity packaging and transportation. The so-called collective packaging refers to the combination of a certain number of products or packages to form a suitable transportation unit for loading, unloading, storage and transportation. Also known as combined packaging or container unit. Collective packaging can improve the loading and unloading speed of the port, reduce the labor intensity of loading and unloading, reduce the transportation cost and save the transportation miscellaneous expenses, better protect the quality and quantity of goods, and promote the standardization of packaging.
inclusion is the assumption that there are two sets a and B
all elements in B are in a Say a contains B
true inclusion is also an element in B, and there are all elements in a, but the only difference is that a ≠ B can be said to include B. (according to what you said, the standard should be that x is a subset of X and a true subset