Final answer:
In database querying, including CMOS-related systems, the percent sign (%) is used as the wildcard character for substituting zero or more characters in a search pattern.
Step-by-step explanation:
In CMOS (Complementary Metal-Oxide-Semiconductor) or in the context of databases and query language, when using a wildcard to represent any number of characters in a search, the symbol typically used is the percent sign (%). The wildcard is a special character that allows you to perform pattern matching in search queries. While the asterisk (*) is often used as a wildcard in some search systems or programming languages, in SQL (Structured Query Language), which is commonly associated with database operations in systems like CMOS, the percent sign (%) is the correct wildcard character for substituting zero or more characters.