I am studying the GRUB Manual and trying out the various install

In one interactive grub session session using the common

grub> root (hd0,0)
grub> setup (hd0)

The descriptive response included this:

install /grub/stage1 (hd0) (hd0)1+15 p (hd0,0)/grub/stage2

I pretty much understand everything this response EXCEPT for the one:


I KNOW this has to do with the 15 blocks of fat_stage1_5 embedded
after the (hd0) boot sector (MBR). What I am having trouble with is
to reconcile this (hd0)1+15 with the formal install command!!!

Here's what the GRUB Manual for install says:

install [`--force-lba'] [`--stage2=os_stage2_file'] stage1_file [`d']
dest_dev stage2_file [addr] [`p'] [config_file] [real_config_file]

So here's my question:

Exactly what does this (hd0)1+15 blocklist item match to in the
command description parameters?????

It is NOT:

dest_dev <--(hd0)
addr <---since it is supposed to be memory address eg 0x8000

So is this *part of* a two-parter dest_dev blocklist such as:

(hd0) (hd0)1+15

If so, please please explain what this really means in terms of the
installation process.

If not, then what is this (hd0)1+15 ?????