The argument names listed here have been reserved by Vladimir Serbinenko
for grub-mkrescue.
Do not use them as options of -as mkisofs or as generic commands.
Keep in mind with generic commands:
Leading '-' is ignored, inner '-' is mapped to '_'.

http://lists.gnu.org/archive/html/grub-devel/2015-04/msg00122.html

Date: Wed, 29 Apr 2015 16:05:04 +0200
From: Vladimir '?-coder/phcoder' Serbinenko <phcoder@gmail.com>
Subject: Re: grub-mkrescue problems in argp_parse
-------------------------------------------------------------------
--arcs-boot
--compress
--core-compress
--directory
--fonts
--grub-glue-efi
--grub-mkimage
--grub-render-label
--install-modules
--label-bgcolor
--label-color
--label-font
--locale-directory
--locales
--modules
--output
--override-directory
--product-name
--product-version
--pubkey
--rom-directory
--sparc-boot
--themes
--themes-directory
--verbose
--xorriso
-?
-k
-------------------------------------------------------------------
Known traditional collisions:
-------------------------------------------------------------------
-o intentionally overloaded
-v unintentional
-d unintentional