When you open DATUM on the clients tab you will find a table with a lot of funny acronyms for which there is no clear explanation on DATUM Github or Ocean website so let me try to figure it out:

First, "Subbed" – maybe that's short for "Subscribed"? The values here look like a combination of letters and numbers, possibly client IDs, followed by a number of seconds how long the client has been subscribed to the server.

"Last Accepted" – the time since the last valid share or block was accepted from this client. The values here are in seconds

VDiff – "Variable Difficulty" might be the current minimum difficulty setting for the client

DiffA (A) – "Difficulty Accepted" The total accepted shares at that difficulty? The number in parentheses could be the count of accepted shares. So DiffA might represent the total difficulty of accepted shares and the number of them

DiffR (R) – "Difficulty Rejected" Similar to DiffA, but for rejected shares. This column shows the total difficulty of rejected shares, their count, and the rejection percentage

Hashrate (age) – The hashrate of the client and the age in seconds indicating how recent the last update was

Coinbase – Usually refers to the address where mining rewards go

UserAgent – The software the client is using. This helps identify the miner software and version.