CD means its a class A low powered station. In a nutshell it has more protection than a low powered station (LP analog LD digital). They also have to be digital now (low powered stations/translators can still be analog right now)
Unlike traditional LPTV stations, class-A stations were given primary status during the transition to digital television (DTV), meaning that a full-service television station could not displace a class A LPTV station from its broadcast frequency (TV channel), except in rare cases. In contrast, traditional LPTV stations often found their frequencies assigned to full-service DTV operations, forcing them to relocate to another frequency. This was especially true in large cities, where available broadcast spectrum was scarce, and LPTV stations found themselves forced to cease operations due to no suitable spectrum
In exchange for the added broadcast protections, class-A stations are required to be more responsible in covering the community they serve. Class-A stations must:
Broadcast a minimum of 18 hours per day
Broadcast an average of at least three hours per week of programming produced within the media market area served by the station
Be in compliance with the Commission's requirements for both LPTV stations and full-power television stations
Broadcast on a core frequency (channels 2 - 51)
Broadcast the minimum required amount of Children's "E/I" core programming
Be capable of airing Emergency Alert System broadcasts when/if the need arises
https://en.wikipedia.org/wiki/Class_A_television_service
