On 04/15/2016 01:02 PM, Uwe Brauer wrote:
>    > On 04/15/2016 11:10 AM, Uwe Brauer wrote:
> 
>    > Not really; it's specific to the distribution part, which you don't
>    > care about. From the metadata in the headers (for single-file
>    > packages) or in …-pkg.el (for multi-file packages) MELPA will build a
>    > tar files that users download through package.el.
> Ok thanks.
> 
> I am sorry to nag, but I find the lack of some manual frustrating.

No problem. Happy to help when I can. Looking at this a bit more, I think what I said earlier needs to be slightly amended. If you have a file whose name matches your package's name, if seems that MELPA will use its headers to generate a package description. Since you don't have a matlab-mode.el, though, MELPA doesn't know where to look.

You can just create a matlab-mode-pkg.el file, and it will grab information from there. I don't generally write these -pkg files by hand. Instead, I just use Cask (https://github.com/cask/cask) to generate them for me.

> If I understand correctly, all I have to do is  to provide a file
> matlab-pkg.el, then automatically the info string will be updated.

matlab-mode-pkg.el, right?

> But I am not sure about its contend. Looking up in packages I installed
> from MELPA (...) does not really help

You could take a look at https://github.com/emacs-helm/helm/blob/master/helm-pkg.el for an example. Here are other examples from my packages:

https://github.com/cpitclaudel/company-coq/blob/master/company-coq-pkg.el
https://github.com/cpitclaudel/biblio.el/blob/master/biblio-pkg.el

The docs of that define-package forms are here: https://www.gnu.org/software/emacs/manual/html_node/elisp/Multi_002dfile-Packages.html . Your confusion regarding version numbers is due to MELPA editing the pkg file when it packages your software. MELPA packages use a different versioning namespace based on the packaging date. IOW, when your package is finally built, MELPA will replace its real version number by the current date and time.