What the different between ST_FOFS and ST_RFOFS in PKTSTOREFLAGS register?

Hello!
Could you please explain what the different between ST_FOFS and ST_RFOFS in PKTSTOREFLAGS Register ?

When i configurate PKTSTOREFLAGS = 0x14 ( RSSI and ST_RFOFS) and than receive and read paket FIFO in case AX5043_FIFOCMD_RFFREQOFFS - every time register contain 0x00.
I have been try put frequency more\less on 200 Hz on second pcb transmitter, but receiver every time return 0x00.

P\S: Modulation PSK, ENCODER = Diff, Speed: 4800

So, if i understand correct for measure the real offset need to use ST_FOFS bit and also after got RX_BUF_NOT_EMPTY interrupt flag read fifo “AX5043_FIFOCMD_FREQOFFS”

Still only one question, is it data (int16_t) contain real freq offset in Hz or to need transfer to Hz using function “axradio_conv_freq_tohz()”