What version of DevonThink Pro 3.0 would compare to DevonThik Pro Office

What version of DevonThink Pro 3.0 (standard, Pro, or Server) would take the place of DevonThink Pro Office version 2.11?

DTPO has a server capability, no? If you never use it, then Pro, otherwise Server.

Sorry, I am not sure how that applies. If I enter data on my Mac, will I still be able to see it and edit it on my iPhone in Pro or does that require server?

Server edition is different in the regard that it has a WEB server. So you can use DT3 online or via intranet and share databases to others via their web browsers. This is Server.

Using iPhone (DEVONthink To Go) and Sync is a separate feature, and Server is not necessary for this.

So what is the “DEVONthink Pro Office”?

That was the 2.x naming for what is now DT 3 server.