When a revision for an object is created, it includes revision text for all of the attributes that changed during the event. There is one exception and that is when an object is created the revision will say "Original version".
The entire revision text for a single revision is limited to 4000 bytes. The maximum revision text for a single attribute change within a revision is limited to 2000 bytes (except a discussion post which is limited to 4000 bytes). If a single attribute's revision change text is more than 2000 bytes the attribute's revision change will say "value too long to display". This usually occurs for description attribute changes since the description field can be large.
Example: DESCRIPTION changed [value too long to display]
When a revision contains multiple attribute changes and the length of the entire revision text is greater than 4000 bytes we truncate the revision text and append to the end of the text " and more ...".