While parsing the input theory and perfoming queries several kinds of errors and warnings can be produced. When using the Unix pipe to connect zdatrtok and zdatrinf, with both modules set to work quietly, minor errors will not be reported to console and so will not be notified. Consult the error file to see them. The error file (like the log file, described in the next section) has a default name but can be renamed via the command-line parameter -e filename. Furthermore both files will be overwritten by zdatrtok, but just appended to by zdatrinf. When using zdatrinf several times without invoking zdatrtok, the error file and the log file will contain all information accumulated from every session since the last invocation of zdatrtok.