The "Considerate Operator's Frequency Guide"
The Considerate Operator's Guide shows frequencies generally recognized for certain modes or activities (all frequencies are in MHz).
Nothing in the rules recognizes a net's, group's or any individual's special privilege to any specific frequency. Section 97.101(b) of the Rules states that "Each station licensee and each control operator must cooperate in selecting transmitting channels and in making the most effective use of the amateur service frequencies. No frequency will be assigned for the exclusive use of any station." No one "owns" a frequency.
It's good practice--and plain old common sense--for any operator, regardless of mode, to check to see if the frequency is in use prior to engaging operation. If you are there first, other operators should make an effort to protect you from interference to the extent possible, given that 100% interference-free operation is an unrealistic expectation in today's congested bands.
ARRL band plans for frequencies above 28.300 MHz are shown in The ARRL Repeater Directory and The FCC Rule Book. For detailed packet frequencies, see QST, September 1987, page 54, and March 1988, page 51.
NCDXF/IARU beacons operate on 14.100, 18.110, 21.150, 24.930 and 28.200 MHz.