SIR is a Slot Information Request, it is used to query the slots held by a given operator at a given airport.
An SIR message is composed of a header, data line and footer. Action code Q is used to query the slots held.
Example of message requesting all arrival and departure flights for AF at LHR
SIR
S09
05FEB
LHR
QAF AF
GI BRGDS
Example of message requesting flights between 01MAY29MAY day 5 for 0800 to 1000
SIR
S09
05FEB
LHR
QQQQ QQQ 01MAY29MAY 0000500 0800 1000
GI BRGDS