The concept of a "calling frequency" or "mode window" is handy for encouraging niche modes and guiding newcomers to the right place to work people with similar interests, but none of it has any basis in regulation or even mutual agreement.  I love to operate AM, but there is no place it is exclusive.  

 

One could just as easily say that the 7295-7300 kHz range is the "USB-on-40m" window, or the "Military equipment window" and it would mean just as much.   

 

If someone is seeking to enforce limiting a part of a band to one niche mode, they are simply wrong.    This issue comes up in regard to the digital operation in in the CW band, variously from both digital and CW operators with a beef.

 

It is interesting that on both 75 and 40 meters the AM activity is spreading out across the phone band.  I first learned about this trend through AF4K Crystals customers who were buying crystals on other frequencies for use with vintage AM transmitters.  They needed additional frequencies to be able to move to the other freqs with their friends.