<para>
This option specifies the number of digits to be used when
writing elevation values.
Precision is the number of digits after the decimal point.  The default
precision is 3.  We limit the number of places we write to improve the
fidelity when round-tripping elevation, reduce file size, and reduce
silliness in files caused by repeating decimals in insignificant
digits.
</para>
<para>
As a guideline, three decimal places is 1 millimeter.
To achieve precision approaching this limit leveling techniques are required.
Precisions beyond this are not currently obtainable.
</para>
<para>
This value is ignored on read and has no impact on the internal
representation of data.
</para>
