Via the element <gc> the value of the respective Varying Permeability Model (VPM) parameter is set. In VPM, gc is the nuclear crushing tension. 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 dyne/cm are used, whereas in UDDF only SI units are allowed. Therefore, units used for gc are kg/s2, given as a real number.
(see also <vpm>)
<!-- 257.0 dyne/cm = 257 * 10^(-3) kg/s^2 --> <gc>0.257</gc>