## 12 Comments and preprocessor directives

A `//` or `/* */` comment that is annotated with + in the leftmost column is considered to be added code. A `//` or `/* */` comment without such an annotation is considered to be a comment about the SmPL code, and thus is not matched in the C code.

The following preprocessor directives can likewise be added. They cannot be matched against. The entire line is added, but it is not parsed.

- `if`
- `ifdef`
- `ifndef`
- `else`
- `elif`
- `endif`
- `error`
- `line`