[O] Export datetree item subtree with its date, not the file's

[Göktuğ Kayaalp]

Hi,

This is my  first post to this  group, so I'm sorry if  I'm skipping any
conventions.  And sorry for the dense subject line,  I didn't want it to
be too long.  Thanks a lot for the hard work on org-mode.

I have  started recently to organise  my lecture notes into  a datetree.
Every now and then I have to  export my notes, usually to pdfs, in order
to share them with friends, or  study/read myself in printed form.  Now,
when I export to pdf an  item, the "\maketitle" header contains the date
from the file's "#+DATE:" thing[1].  I'd like it to contain the date for
the current  item, i.e. if  it is  under the "***  2015-09-16 Wednesday"
heading, the pdf to have "16 Sep 2015".   Now I guess that I can do some
temporary-buffer hack to make this happen, but I wonder if there already
exist a /normal/ way to achieve this.

My overall structure is like this:

    # $Id: Italianistica.org,v 1.5 2015/09/30 18:08:27 gk Exp gk $
    #+TITLE: Appunti di Italianistica
    #+STARTUP: contents
    #+OPTIONS: toc:nil tags:nil
    #+LaTeX_CLASS: gk-appunto
    #+DATE:
    * 2015
    ** 2015-09 September
    *** 2015-09-16 Wednesday
    **** İtalyanca Dil Uygulamaları I :2015_2016:ITDE2016:
    [2015-09-16 Wed]
    
    amare \ne voler bene
    
    _amare_ si usa quasi sempre _all'interno di una coppia_
    
    _voler bene_ si usa tra _amici, parenti, ecc._


When  I export-subtree  the bottommost  entry, I  want the  date in  the
exported pdf  to be 2015-09-16,  not today,  nor the date  in "#+DATE:",
which is  deliberately empty to  not let a wrong  date to appear  in the
exported file.

I tried  setting a date property  which didn't have an  effect, and also
adding a "#+DATE:  [a date...]" under every lecture  note entry heading,
in which case the  date of the last entry in the file  got used, so if I
exported the notes from 2015-09-16, and the last time I added a note was
the 19th, the exported file had the date 2015-09-19.

So how can I, if I can at all, achieve what I want without tucking the
tree into a temp buffer, adding the correct #+DATE into it, copying the
org header and exporting?  Is there a standard way to achieve this?

Thanks in advance,
-goktug



[1] Property?  I don't really know what these are called.