Hi Tom,

Thanks for going through the replies so far and refining your thoughts.

> *snip a whole bunch of comments*

I think I’m of the same mind as you that if we try to mentally separate Org the
markup format and Org the emacs mode, the format should not specify the
interpretation of the :tangle-mode value.

I think the best way to have it would be,
⁃ Org the format, :tangle-mode takes a value representing the file permissions
  the tangled file should have. Optional: here are some common examples that
  might be recognised
⁃ Org the emacs mode, :tangle-mode’s value is interpreted like so (…)

> That said, reducing the number of forms as Eric suggests would
> be a happy medium.

Indeed, I’ve basically supported every form I could think of. I’m currently
inclined to cut it down to:
• 755
• “rwxrw-r–” (`ls -l' style)
• chmod style with `org-babel-tangle-default-mode' and `file-modes-symbolic-to-number'

Maybe with (if anybody says they would like this)
• #o755 (elisp octal)
• 0755 (C octal)
• “rwx” = user perm, bit-or’d with `org-babel-tangle-default-mode' for the rest
  (i.e. `org-babel-tangle-default-mode', but not exceeding the user perm)

All the best,
Timothy