Prefix and Suffix, when set on the Source, appear in the post no matter where it ends up going (Twitter, Facebook, LinkedIn, etc.) You may indicate the source of a post - "Blog", for example.
Prefix and Suffix, when set on the Destination, are only sent to that destination. For Twitter you might include manual hash tags, for example.
If you include both Source and Destination prefix and suffixes, they're displayed on the resulting posts like this:
[Destination Prefix] [Source Prefix] [Item Content - Title/Body/Url] [Source Suffix] [Destination Suffix]
We've added prefix/suffix support on the source side. We continue to support prefix/suffix on the destination side as well.
Further, you can use source and destination prefixes/suffixes in a single route. If you were to use all four fields in a single route the output would be:
[Destination Prefix] [Source Prefix] Headline Body URL [Source Suffix] [Destination Suffix]
If used, the destination prefix/suffix will always appear at the very beginning and very end of the output string -- effectively wrapping the rest of the content.
This approach provides a tremendous amount of flexibility and control over prefixes/suffixes. Post away!