1 of 1 people found this helpful
Some users set that variable so they can use batch (command line) Calibre with a rule file that was created by Calibre Interactive.
Calibre Interactive creates a special rule file that contains options and statements that were set within the Calibre Interactive GUI, and it also contains an "include" statement referencing the original rule file. There may be statements in the special rule file from the GUI that are duplicated in the original rule file. Duplication of certain statements is typically a syntax error, so a special mechanism was developed to handle this situation. The MGC_CALIBRE_INTERACTIVE variable, and a related statement (DRC ICSTATION YES) in the special rule files (often called control files) from the GUI work together to accomodate the potential duplication of statements between original rule files and the control file created by Calibre Interactive GUI.
NOTE: if the original rule file was called "myrules" then the control file would be called "_myrules_" and both can be viewed in a text editor.