de> : Identification for every unit.</p></li>
<li><p><code>x</code> : Lifetime characteristic.</p></li>
<li><p><code>status</code> : Binary data (0 or 1) indicating whether a unit is a right
censored observation (= 0) or a failure (= 1).</p></li>
<li><p><code>rank</code> : Filled with <code>NA</code>.</p></li>
<li><p><code>prob</code> : Estimated failure probabilities, <code>NA</code> if <code>status = 0</code>.</p></li>
<li><p><code>cdf_estimation_method</code> : Specified method for the estimation o