Manifest files serve to provide meta information for a library in a structured way. Their syntax is in JSON. They have a more "informal" part (keyed info), which is more interesting for human readers, and a technical part (named provides) that is used in the processing of generator configurations. Here is a brief sample with all the possible keys:

{
  "info" : 
  {
    "name" : "Custom Application",
 
    "summary" : "Custom Application",
    "description" : "This is a skeleton for a custom application with qooxdoo.",
 
    "keywords" : ["custom"],
    "homepage" : "http://some.homepage.url/",
 
    "license" : "SomeLicense",
    "authors" : 
    [
      {
        "name" : "First Author (uid)",
        "email" : "first.author@some.domain"
      }
    ],
 
    "version" : "trunk",
    "qooxdoo-versions": ["trunk"]
  },
 
  "provides" : 
  {
    "namespace"   : "custom",
    "encoding"    : "utf-8",
    "class"       : "source/class",
    "resource"    : "source/resource",
    "translation" : "source/translation",
    "type"        : "application"
  }
}

The file paths of the class, resource and translation keys are taken to be relative to the directory of the Manifest file. The namespace attribute can be overridden in the importing config file (in the library key).