Attachment Type: For referring to data content defined in other formats.

Attachment
contentType
Mime type of the content, with charset etc.
data
Data inline, base64ed
url
Uri where the data can be found
size
Number of bytes of content (if url provided)
hash
Hash of the data (sha-1, base64ed)
title
Label to display in place of the data
creation
Date attachment was first created
height
Height of the image in pixels (photo/video)
width
Width of the image in pixels (photo/video)
frames
Number of frames if > 1 (photo)
duration
Length in seconds (audio / video)
pages
Number of printed pages