Most people treat library categories as an organisational convenience. In PlayOnRadio, certain category codes carry behaviour.
Codes that change the audio
A track whose rotation category code begins with ADS, ID or VT is classified as imaging rather than music — commercials, station IDs and voice tracks respectively.
That classification changes the transition rules. Music fades out underneath it while it holds at unity gain, and it is hard-cut rather than faded when the next music item begins.
So a commercial categorised as ADS-LOCAL automatically sounds like a commercial should. One left in a music category will fade in from silence, which is exactly the amateur-sounding artefact you were trying to avoid.
Naming with intent
The practical consequence: pick your category codes deliberately, using the prefixes for anything that is imaging. It is a naming convention that reaches all the way down into the audio engine.
Voice tracks and jingles are also classified by their track type directly, so a jingle added from a button is treated correctly regardless of category. The code prefixes cover the library and rotation path.
Scheduling the breaks
Commercial slots sit in a rotation clock like any other slot, with a category and a target duration. Generate the hour and the breaks are placed with the music.
Fixed-time spots — a sponsor bed at a specific minute — belong on the clock wheel instead, as a file slot.
Proving it aired
This is where categories pay for themselves a second time. The airplay compliance window reports plays per hour and category performance against rotation targets, with an overall compliance percentage.
If a sponsor asks whether their spot ran the agreed number of times, that is a report rather than a search through logs.
Keeping counts honest
Repeat rule sets can exempt jingles and voice tracks from separation counting. A station ID every twenty minutes is the format working, not a repetition problem — and counting it as one would distort the separation maths for actual music.