Assets in Moing

Here are the sorts of assets I envision us being able to work with in Moing:

1. Basic Assets
   Basic assets are standalone assets, normally created in other programs.
   
1. Still Images
   Individual still images; a PNG file, for instance. The distinguishing characteristic of a still image is that it does not change over time and has no fixed duration.
   
2. Clips
   Sound or moving video (with or without sound); think AVI or WAV files (I don't really know which specific formats we will support yet).
   
2. Composite Assets
   Composite assets are normally created and edited in Moing, and amount to collections of other assets which are stacked in some z-ordering and come and go over time.
   
1. Sequences
   Assets are always rendered full-frame; sequence editing works more or less like in a traditional non-linear editor.
   
2. Scenes
   Assets are explicitly positioned on the field and can be scaled, rotated, distorted, and connected together with armatures.
   

All assets exist as individual files and the project as a whole is represented by a single file which references (or contains?) a top-level asset (e.g. a "master sequence") which references other assets and so on down.