This is a **compiler macro**. The `{$I %...%}` syntax inserts a compiler-defined value. `%FPCVERSION%` expands to the Free Pascal version string (e.g., `'3.2.2'`). `%FPCTARGETOS%` expands to the target operating system (e.g., `'Windows'`, `'Linux'`, `'Darwin'`). These are Free Pascal extensions, not