Currently "template_solidpart" and "template_designasm" can only be set to a path of a .prt file.
It does not seem to be possible to set it to none/empty, and force the user to select a template form the list.
We have divisions that use Metric and Imperial, and so have a start part for each. We don't want to specify one or the other as default as they may be used by accident. We don't want to have to manage 2x config.sup files either.
We want the default to be none so the user has to make a conscious selection each time.