riables, and <code>c(0, 0.6)</code> for
discrete variables.</p></dd>


<dt>oob</dt>
<dd><p>Function that handles limits outside of the scale limits
(out of bounds). The default replaces out of bounds values with NA.</p></dd>


<dt>na.value</dt>
<dd><p>Missing values will be replaced with this value.</p></dd>


<dt>trans</dt>
<dd><p>Either the name of a transformation object, or the
  object itself. Built-in transformations include "asn", "atanh",
  "boxcox", "exp", "identity", "log", "log10", "log1p", "log2