What is a ProjectWise "Refresh" release?

It's a complete new install of ProjectWise. The refresh releases are typically bug fixes and merging in of stuff previously released as an add-on (e.g. typically new autodesk integration is released as an add-on, then merged into a single installer at the next refresh.)

until this refresh 3.3 Bentley has always released servers, admins and clients. This refresh has no server installs.

we typically run the client through our internal testing, then replace our current installation with the new version but we don't upgrade everyone unless it fixes a bug we've run into, or we've decided we have too many versions in the environment and want to standardize.

I have zero idea if this is documented anywhere.

If 3.3 (Build 329) doesn't include any server installs, can it be used to upgrade PWIS from Build 140 up to Build 329?

The latest server version is 10.00.03.280 (Update 3.2). You can update your server to that using the ProjectWise Server installs for that version.

Update 3.3 (10.00.03.329) has no server installs, just ProjectWise Explorer and ProjectWise Admin. This version of Admin can only admin ProjectWise integration server 10.00.03.280.

Thank you, Kevin.  Your last comment on Update 3.3 was especially helpful.