Also known as the "General Roaming Calling Frequency" because each day the calling frequency changes, hence "roaming", and "general" because it is for any CW calling use.
Which Frequency?
101nm.5 kHz where nm is the current UTC date.
Example, today's UTC date is the 7th, then it would be 10107.5 kHz. If the date is the 31st, it'd be 10131.5 kHz.
What Rules?
No more than 3 3X3 calls within any 5 minute period and QSY upon establishing contact.
This is because many stations will be listening to this frequency, sometimes using narrow filter with the squelch up, and repeated calls from the same station will defeat the purpose.
On establishing contact stations should agree on a QSY frequency or drift at least 200Hz off.