gptid's in fstab while installing FreeBSD using ISO

[varanasi sainath]

Hi All,

How do I get gptid's as default in fstab while installing using FreeBSD iso
file (Virtual,machine installation) ?
Is this possible currently?
if not how do I achieve this?
I use guided partitioning while installing - If I were to tweak in to the
source code which files or drivers I should be focusing on?
which drivers write the contents of fstab?

PS: any reason why we use device names in the place of gptid's as default
in fstab.

Thanks,
Sainath.