The Anatomy of a Package

Package Structure

Packages are simply ZIP archives with a .yak extension. Take this simple example…

├── manifest.yml
├── Howler.rhp
├── Howler.rui
├── HowlerCommon.dll
├── HowlerGrasshopper.gha
└── misc/
    └── LICENSE.txt


  1. Packages must have a top-level manifest.yml file. Details about the manifest can be found in the Manifest Reference Guide.
  2. Any plug-ins (.rhp, .gha, .ghpy files) must be in the top-level directory so that Rhino and Grasshopper can find and load them
  3. Package version numbers must either follow Semantic Versioning 2.0.0 (e.g. 1.1.0-beta) or System.Version a.k.a. Microsoft’s four-digit standard (e.g. It’s recommended to use Semantic Versioning because it allows package authors to specify prerelease versions. These are handy for limited testing, since by default the latest stable version is installed.


For a single package version it’s possible to upload multiple “distributions” to target different Rhino versions and platforms. This information is encoded in a “distribution tag” that is appended to the filename of the package, e.g. example-1.0.0-rh7-win.yak.

The distribution tag consists of an “app” identifier and version, and a platform. Currently the only supported apps are rh and any – Grasshopper ships with Rhino so it doesn’t need its own identifier. Unless the app is any, an app version must be included in the form <major>_<minor>. The minor version is optional and is useful if a plug-in relies on an SDK change made in a service release. The platform can be win, mac or any (i.e. cross-platform).

A few examples…

  • rh7-win - Rhino 7 for Windows >= 7.0
  • rh6_14-mac - Rhino 6 for Mac >= 6.14
  • rh6_9-any - Rhino 6 (both platforms) >= 6.9
  • any-any - anything goes! (existing behaviour)

When installing packages, the package manager checks whether a compatible distribution exists for the requested version. Only package versions that have at least one compatible distribution will show up when the _PackageManager command is run in Rhino 7+.

The updated server works seamlessly with existing packages and old versions of Rhino. Pre-existing versions on the server (without distributions) will be treated as any-any when installing. New package versions that do not include a distribution tag, e.g. those created by previous versions of the CLI, will also be treated as any-any when publishing.

Next Steps

Now that you’ve have seen what is in a package, why not create a package: