Hi Robert, Please see my follow up post with a more detailed description and a (as I find) already better solution. In summary, it is about providing a way to store data in org-mode which is not intended to be read/modified by humans. Your idea would be one part of it and I was thinking of that too. > I could see a use for a "blob" property. Suppose I have a JPEG of > someone's portrait that I want to incorporate into a contact's > properties. Some mechanism to indicate: Unfortunately, I notice that Emacs and org-mode can easily slow down for large documents (I noticed, e.g. by using thousand lines of (collapsed) code blocks) . I frighten that an JPEG or PNG which would easily fill hundreds or thousands of (hidden) lines might slow down org-mode. That is, if there would be such a function, one would have to make sure it does not influence the performance.
Torsten