#+ATTR_MY-ASCII: in derived backend?

[Thorsten Jolitz <tjolitz@gmail.com>]

Hi List, 

do derived backends set their attributes always via the 

,--------------
| +ATTR_BACKEND:
`--------------

construct of the parent backend and don't have their own 

,--------------
| +ATTR_MY-BACKEND:
`--------------

construct?

The following excerpt from the manual suggests this - and I actually
tried it out and the latter is not added as ':attr_my-backend "value"'
to the property list of the following element, but the former is added
as ':attr_backend "value"'.

,-----------------------------------------------------------------------------
| As an example, imagine we want the ascii back-end to display the
| language used in a source block, when it is available, but only when
| some attribute is non-nil, like the following:
|
|      #+ATTR_ASCII: :language t
|
| Because that back-end is lacking in that area, we are going to create a
| new back-end, my-ascii that will do the job.
|
|      (defun my-ascii-src-block (src-block contents info)
|        "Transcode a SRC-BLOCK element from Org to ASCII.
|      CONTENTS is nil.  INFO is a plist used as a communication
|      channel."
|        (if (not (org-export-read-attribute :attr_ascii src-block :language))
|          (org-export-with-backend 'ascii src-block contents info)
|        (concat
|         (format ",--[ %s ]--\n%s`----"
|                 (org-element-property :language src-block)
|                 (replace-regexp-in-string
|                  "^" "| "
|                  (org-element-normalize-string
|                   (org-export-format-code-default src-block info)))))))
|
|      (org-export-define-derived-backend 'my-ascii 'ascii
|        :translate-alist '((src-block . my-ascii-src-block)))
`-----------------------------------------------------------------------------

But OTOH, aren't things like 

,--------------
| +ATTR_BEAMER:
`--------------

working although its a derived backend? 

--
cheers,
Thorsten