shortname
For custom layers only, use this parameter to specify the layer's short name, which is used internally by OpsWorks Stacks and by Chef recipes. The short name is also used as the name for the directory where your app files are installed. It can have a maximum of 32 characters, which are limited to the alphanumeric characters, '-', '_', and '.'.
Built-in layer short names are defined by OpsWorks Stacks. For more information, see the Layer Reference.