AGDX is an update to the original AGD4.7 and is fully cross-compatible with over 100 new additions and a number of bugfixes. You can find a user group on Facebook, search for 'AGDX user group'. Thanks!
To activate these commands, you just need to add a simple assembly instruction, like so:
;detect block at line 5, column 7 LET LIN 5 LET COL 7 GETBLK .50 .53 .125
This will place the value of the block type at line 5, column 7 into the variable OBJ, which can then be tested.
If you want to use another variable, simply change the number 53 to a number between 29 and 48, where A=29,B=30, all the way to T=48. This will put the value of the current block at the LIN / COL specified in to the variable of your choice.