VHF Data Exchange System messages

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Physical link	Msg	Title	Description	Priority	Access scheme	Communication state	Transmitted by
ASM	0	Broadcast AIS ASM Message	Encapsulated AIS ASM messages	not applicable	RATDMA	N/A	Base station
ASM	1	Scheduled Broadcast Message	Broadcast data using communication state	not applicable	RATDMA, FATDMA, MITDMA	MITDMA	Mobile station, Base station
ASM	2	Broadcast Message	Broadcast data with no communication state	not applicable	RATDMA, FATDMA	N/A	Mobile station, Base station
ASM	3	Scheduled Individual Addressed Message	Individual addressed data with communication state. Requires acknowledgement	not applicable	RATDMA, FATDMA, MITDMA	MITDMA	Mobile station, Base station
ASM	4	Individual Addressed Message	Individual addressed data with no communication state. Requires acknowledgement	not applicable	RATDMA, FATDMA	N/A	Mobile station, Base station
ASM	5	Acknowledgment Message	This message is used to provide and acknowledgment for one or more addressed messages	not applicable	RATDMA, FATDMA, MITDMA	N/A	Mobile station, Base station
ASM	6	Geographical Multicast Message	Addressed to a group of stations defined by their geographical location with no communication state. No acknowledgment required.	not applicable	RATDMA, FATDMA	N/A	Mobile station, Base station