Hi, I'm using an object Y position field as an attribute for a block. This is what I use: %<\AcObjProp.16.2 Object(%<\_ObjId 2118086344>%).InsertionPoint \f "%lu2%pt2%pr4%ps[+, M]%ct8[0.001]">% What I would like to do is an arithmetic operation of addition, something similar to how 'CAL works. In this particular case I would like to add the value of 100,000 before the conversion factor, or 100 after the conversion factor. Thanks.

Yes, you can do this. See the tip:
http://www.cadforum.cz/cadforum_en/qaID.asp?tip=6381
 
The resulting expression will look similar to:
%<\AcExpr (100+%<\_FldPtr 305306904>%) \f "%ps[+, M]">%
and
%<\AcObjProp Object(%<\_ObjId 2129671616>%).InsertionPoint \f "%lu2%pt2">%