From OpenSCADAWiki
The same debug messages (the suffix is "Debug" or the level is 0), on Work version, will be allowed to observe only after the debugging enabled, the field "Least level" set to "Debug (0)" (Fig. 6.8), and category(es) of the messages checked (Fig. 6.9), for the details read here! But the debug messages enabling and disabling allows you to include the debug messages permanently into the procedures with the proper category of the place. All other, not debug, messages will show anytime, for levels more or equal to the globally set (Fig. 6.8).