That is, "registering a customer" is required by the "buying items in shopping cart" use case, but it simply precedes the "browsing the catalog" use case -- it's not a requirement.

即，“购买购物车中的商品”用例必须要使用“注册用户”，但“注册用户”只是在“浏览商品目录”之前-- 它并不是一个必要条件。

youdao

What the winning bidder would be buying (stated the catalog) were reliquaries, not the relics they contained.

FORBES: Magazine Article

Aspect tracks the form, function and price of more than 10 million components, then meshes this mega-catalog with a client's data on preferred suppliers, inventory and buying habits. 3Com Corp. used it to learn that six departments were paying different prices for the same component from different suppliers.

FORBES: Chain gang