I doubt it would be observed. Note that 10-10 contests on 10 meters
require that no contest activity be between 28490 and 28510, but there
are nearly always stations CQing for the contest in that range. ARRL
10M contests used to have a contest free zone of 28300 to 28350. It was
often violated and it turned out that LU Novices were confined to those
50 khz, so it prohibited them from participating. The no contest
subband was dropped.
Many contests in Europe require participation only in contest bands as
defined by IARU region one. That means no contest activity above 14060
on CW and none above 14300 on phone. There are restrictions on some
other bands as well, notably no SSB activity below 7040 on 40 meters.
Last weekend, in the RSGB IOTA contest, the rules for which do restrict
activity to certain frequencies, there were CQ Contests well above 14060
and 14300. It is doubtful that everyone doing that knew they were
violating a contest rule. People can get on the air, hear the contest,
and operate the contest as they understand it without actually reading
and understanding the rules. I doubt that there is any organized
monitoring done to identify and disqualify violators. I have
OCCASIONALLY suggested to a 10-10 member that he or she should not be
calling for contest QSOs between 28490 and 28510. Any organized
monitoring of the frequencies during the contest would mean that the
monitors would not themselves be able to enjoy the contest.
We know that it is technologically possible to record a section of a
band during the contest and listen to it afterward, but I have never
heard of it being done for this purpose.
It is likely that strict compliance with a small segment requirement in
a contest when the licensing authority allows wider use of the band
would not be widely observed.
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