What does the letter ?r? stand for in /dev/sr0?

[Mark Syms]

On Mon, 02 Nov 2009 11:57:30 +0000, ubuntu-users-request at lists.ubuntu.com
wrote:
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> Lo?c Greni? wrote:
>> 2009/11/1 Detlef Lechner <Detlef.Lechner at gmx.net>:
>>> Hi,
>>>
>>> what does the letter ?r? stand for in /dev/sr0?
>>> (/dev/scd0 is a link to /dev/sr0.)
>> 
>>    Read-only ?
> 
> Hm.
> 
> Detlef

Removable - i.e. used on CD/DVD drives.