The level of semantic auditing affects which messages are issued for a DCL file.
If you set the audit level to 3, an alert dialog box is displayed with a warning message when an error is encountered. You can see this for yourself by inserting the following line at the beginning of a DCL file:
dcl_settings : default_dcl_settings { audit_level = 3; }
Try viewing a dialog box with an error, such as adding a duplicate attribute. You will be alerted to view the acad.dce file, which contains the following messages:
=== DCL semantic audit of C:/PROGRA~1/AUTOCA~1/VLISP/$vld$.dcl ===
At lower (less discriminating) levels of semantic auditing, AutoCAD does not look for redundant attribute definitions and the dialog box displays normally. Remove the duplicate attribute statement from the DCL to correct the situation you were warned about.