How to control Name of boot images for pxeboot

Problem:
pxe boot images are deployed as:
MySite_centos-eONUB8k2zBoY-initrd.img and
kstm_centos-eONUB8k2zBoY-vmlinuz

It seems somehow the prefix of the name is taken from corresponding configuration of installation medium, I called it MySite_CentOS.

Expected outcome:
something like: CentOS---…

Foreman and Proxy versions:
1.23

Actually it is not important, since same names are used in pxe boot templates. However, in order to keep overview about images it would be nice to have human friendly names.