Dial or centre frequency?
Should you want to know what the calling frequency for PSK31 or Olivia is on a certain
band, you can find it online.
It's particularly important for Olivia, as often the signals decoded will be below the noise level and so agreed
"channels" for Olivia work have been agreed upon.
Simply scanning round for Olivia transmissions might mean that you miss them
It's usually given in one (or both) of two formats - dial frequency or centre frequency.
An example can be found at https://www.oliviadigitalmode.org/
For the 20m band, it gives 14.0715 MHz as the dial frequency, and 14.0730 as the centre frequency.
Dial frequency
However, the dial frequency often assumes that your waterfall offset is 1.5 kHz.
As a quick recap, when working digimodes, your actual frequency is your dial frequency PLUS your waterfall frequency.
So giving a dial frequency is pretty useless.
Centre frequency
The centre frequency is the ACTUAL frequency that you will be transmitting and receiving on. It's completely unrelated to whatever the waterfall frequency is set to, which is a matter for local taste. I personally use a waterfall offset of 1 kHz.
In the image below, you can see that the radio (dial) frequency is 14.072 MHz, the waterfall is 1 kHz, and thus
the centre frequency is 14.073 MHz.
The frequency displayed in the smaller font size is actually the more important one - the centre frequency.
If I was the developer of a digimode program, I would swap the two frequencies around