Hashes (#) in /boot/grub/menu.lst

/boot/grub/menu.lst is used to customize the grub bootloader. Similar to every configuration file, a hash # at the beginning of a line means it is a comment, for humans to read only. The application will ignore it. Well not quite. A special section in /boot/grub/menu.lst defaults the rule: the automagic kernel list.

### BEGIN AUTOMAGIC KERNELS LIST
## lines between the AUTOMAGIC KERNELS LIST markers will be modified
## by the debian update-grub script except for the default options below

##DO NOT UNCOMMENT THEM, Just edit them to your needs

## ## Start Default Options ##
<snip>
## controls how many kernels should be put into the menu.lst
## only counts the first occurence of a kernel, not the
## alternative kernel options
## e.g. howmany=all
##      howmany=7
# howmany=all
<snip>
## ## End Default Options ##

2 hashes mean the line is a comment, 1 hash is a default option, no hash is a kernel entry. grub is special, it names drives and uses hashes its own way :)

References

UF Thread
hermanzone pages