CAD tip # 5128:

Despite that LT does not support the FIELD command, you can insert the field codes in the plain DTEXT command and these fields are still dynamically interpreted/updated.

So you can e.g. insert an automatic value containing the DWG file name - just copy the following line to the contents of a DTEXT entity:

%<\AcVar Filename \f "%fn6">%

Or put the last save date or the last plot date in your drawing:

%<\AcVar SaveDate \f "dd.MM.yyyy h:mm tt">%
%<\AcVar PlotDate \f "%#c">%