Form of Definitions File (GNAT User’s Guide for Native Platforms)

#### 3.10.2.4 Form of Definitions File ¶

The definitions file contains lines of the form:

    symbol := value

where `symbol` is a preprocessing symbol, and `value` is one of the following:

- Empty, corresponding to a null substitution,
- A string literal using normal Ada syntax, or
- Any sequence of characters from the set {letters, digits, period, underline}.

You may also place comment lines in the definitions file, starting with the usual `--` and comments may be added to the end of each definition line.