The semantic structure of a programming language encompasses the rules and meanings that govern how code is interpreted and executed. Among the options listed, execution order does not typically form part of the semantic structure. Instead, it relates more directly to the control flow of a program, which dictates the sequence in which statements are executed rather than the meanings or interpretations of those statements.
Type checking, parameter matching, and variable scoping all fall within the realm of semantic analysis. Type checking ensures that variables are used in accordance with their defined types, parameter matching verifies that function calls adhere to defined parameter specifications, and variable scoping determines the visibility or lifetime of variables within certain contexts. These aspects are essential to understanding how code behaves and interacts during execution, solidifying their place within the semantic structure, whereas execution order is more focused on the procedural aspect of programming rather than semantic meaning.