Paul Jones has a post to his site with a proposal for a standard structure for PHP packages to help provide consistency across the PHP package ecosystem. His proposal - the Package Development Standards initiative - defines the structure of the repository instead of conventions to be used in the package itself (like naming or object structure).

The new pds/skeleton (and the related research) for public review. If you are a package author, you are invited to post your comments and criticisms of the publication as issues on the relevant Github repository.

The pds/skeleton publication describes a set of standard top-level PHP package directories and files. If you are an author of more than three packages on Packagist, chances are you already follow the standard! That’s because PDS initiative researches the PHP package ecosystem to recognize commonly adopted development practices.

He's putting it out there for public review for now until he can get some feedback from the community on the structure and recommendations made. He also recommends going a head and adding "pds/skeleton" to your "require-dev" section to indicate your compliance to the suggestions he's presented.