[O] how to compare org-mode version to current file needs

[Olaf.Hamann]

Hello,

is there any org-mode expression for saying "this org-file needs 
org-version > xxx"

which will compare current needs of the file to used orgmode at org-file 
startup
and present a little message to the user?

I think, it could be done with an emacs-lisp block comparing org-version 
to a certain string,
but I have to express

this org-file needs org-version >=  "Org-mode version 7.5 
(release_7.5.47.g4d9f2.dirty)"

and I don't know what or how to compare (string compare or git timeline 
or so?).

Thank you very much in advance,
Olaf