According to Artur Meinild’s answer here, the "day of month" and "day of week" fields of a crontab are mutually exclusive. However, according to
man 5 crontab (for cronie, if it matters):
Commands are executed by cron(8) when the ‘minute’, ‘hour’, and ‘month of the year’ fields match the current time, and at least one of the two ‘day’ fields (‘day of month’, or ‘day of week’) match the current time
So, is the following line an error, or instructions to run
/bin/true on every Wednesday plus the second day of each month?
* * 2 * 3 /bin/true