using these rules.
</p>


<h3 id="Identifiers">Identifiers</h3>

<p>
Identifiers name program entities such as variables and types.
An identifier is a sequence of one or more letters and digits.
The first character in an identifier must be a letter.
</p>
<pre class="ebnf">
identifier = letter { letter | unicode_digit } .
</pre>
<pre>
a
_x9

          <version>4.0.0+</version>
          <required>true</required>
          <identifier>true</identifier>
          <description>
            A unique identifier for a repository. This is used to match the repository
            to configuration in the {@code settings.xml} file, for example. Furthermore, the identifier is
            used during POM inheritance and profile injection to detect repositories that should be merged.

    public static final String LABELS_CITY = "{labels.city}";

    /** The key of the message: Teletex Terminal Identifier */
    public static final String LABELS_user_teletexTerminalIdentifier = "{labels.user_teletexTerminalIdentifier}";

    /** The key of the message: Teletex Terminal Identifier */
    public static final String LABELS_TELETEX_TERMINAL_IDENTIFIER = "{labels.teletexTerminalIdentifier}";

                * `name`: (`str`) **REQUIRED** (if a `license_info` is set). The
                    license name used for the API.
                * `identifier`: (`str`) An [SPDX](https://spdx.dev/) license expression
                    for the API. The `identifier` field is mutually exclusive of the `url`
                    field. Available since OpenAPI 3.1.0, FastAPI 0.99.0.

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