Simul can incorporate changes made offline back into its revision history. This can be handy for a number of reasons:
To upload a document, select the appropriate document from the documents console.
Select the most appropriate revision, this is usually the version you used to download a copy.
Select the "Upload a version" options from the "More actions" menu near the "Open in Word" button:
Select your file to upload and press "Upload":
Your uploaded document will then appear as a regular revision.
If the offline version is from a third party or potentially out of sync, you can upload the document into a separate branch:
This will cause the uploaded document to exist in its own branch like so:
The version will be labeled that it is an offline copy and can be merged with your documents as described here.