As described in section 5.4.3.1.3 of ISO13239:
In ARM and ABM, the P bit set to "1" shall be used to solicit a response, at the earliest respond opportunity, with the F bit set to"1".
NOTE : For example, if the primary/combined station requires positive acknowledgement that a particular command has been received, it sets the P bit in the command to "1". This forces a response from the secondary/combined station as described in 5.4.3.1.6.
(The reference to 5.4.3.1.6 must be a typo, as that section doesn't exist...)