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<!doctype html>
<html>
    <head>
        <title>MS Edge bug with fields pattern</title>
    </head>
    <body>
        <form method=GET action=#/>
            <p>The field below requires the following pattern:
            <pre>[0-9a-zA-Z]|[0-9a-zA-Z_]{2,40}</pre>
            </p>
            <input type="text" pattern="[0-9a-zA-Z]|[0-9a-zA-Z_]{2,40}"/><br/>
            <br/>
            <input type="submit"/>
        </form>
    </body>
</html>