Via the element <r0> the value of the respective Varying Permeability Model (VPM) parameter is set. In VPM, r0 is the minimum bubble radius excitable into growth. In the original literature (D.E. Yount, D.C. Hoffman, On the Use of a Bubble Formation Model to Calculate Diving Tables, Aviation, Space and Environmental Medicine, February 1986) the units micrometer are used, whereas in UDDF only SI units are allowed. Therefore, units used for r0 are metre, given as a real number.
(see also <vpm>)
<!-- 1 micrometre --> <r0>1.0e-6</r0>