# MetaData we need to represent

* embedded in the file/data object contents 
* external, provided by filesystem/container 
* external, provided by user/annotation apps etc. these maybe stored in e.g. filesystem extended attributes and may be stored in a separate db. 

## Embedded in the file/data object contents


### Generic content

Content creators 

* author(primary contributor) 
* contributor(secondary contributor) 
* mantainer 
Author's annotation/categorization of the content 

* subject 
* title 
* description 
* comment 
* keywords 
* creation/last modification time 
* IDs(various) 
* plain-text representation for indexing purposes(not a good fit here, but it's closest) 
Content legal info: 

* copyright 
* disclaimer 
* license type 
* license text 
Content relations to other content: 

* containment 
* dependency 
* link/mention 
* conflicts?    -- a must for software.  do they apply to generic content? 
* supercedes? 
Content generator software specifics: 

* software name(or better yet semantic link :) 
* software options 
Content format description/specifics: 

* encoding/code page(transitional until obsoleted by UTF8). 
* languages 
* format subtype like BMP has or to specify format extensions. 

## External, provided by filesystem/container

Location/ID 

Creation/access/modification time 

ACL(access control) 


### Media

Generic 

* sample format 
* codec 
* duration 
* frame count 
* FPS 
Audio 

Music 

* ID3 is designed to tag music 
Visual 

* image size 
* aspect ratio 
* resolution 
Video 

* Frame count 
* FPS 
Audio+Video 

Photo: 

* EXIF is a good base for this 
===Documents=== ===Messaging=== Generic message 

* Recipient 
Email 

* to 
* cc 
* bcc 

### Contacts


## External, provided by user/annotation apps etc. these maybe stored in e.g. filesystem extended attributes and may be stored in a separate db.

User's annotation of content similar to content author's one. Note: To a degree file name is a part user's annotation.  

Quality etc ratings 

Usage intensity 


# Data types

Object 

Content 

Document 

Text 

Media 

Audio 

Music 

Image 

Photo 

Video 

Software 
# Source type

file 

attachment 

message