Title: FIS - Reception of a Cancel Contracts Accept APDU

PDR Reference:				97100034
Originator Reference: 			cancelall
SARPs Document Reference: 		FIS SARPs, Sections 2.4.5.3.11.1, 								2.4.5.3.10.2, 2.4.4.2.1
Status: 					ADOPTED
PDR Revision Date: 			29/10/97 (SUBMITTED -> ACCEPTED)
                                	28/11/97 (ACCEPTED -> PROPOSED)
					16/12/97 (PROPOSED -> RESOLVED)
PDR Submission Date:			27/10/97
Submitting State/Organisation: 	Aerospatiale
Submitting Author Name: 		Chapirot, L
Submitting Author E-mail Address: 	lucie.chapirot@avions.aerospatiale.fr
Submitting Author Supplemental 
Contact Information:
SARPs Date:					IV1.1, March 97
SARPs Language: 				English

Summary of Defect: 

There are three errors in the way the ASEs are handling the cancellation of contracts.

1/ Editorial error in section 2.4.5.3.11.1 c):
The ground CL module should create an UplinkAPDU instead of a DownlinkAPDU.

2/ Exception handling for FISCancelContracts service.

Section 2.4.5.3.10.2 is incomplete. 
Let's assume that the types of contracts specified in the received [FISCancelContractsAccept] APDU do not match the ones specified in the [FISCancelContracts] APDU previously sent. The actions to be taken by the ASE in that situation are not described.
This is a protocol error introduced by the ground ASE which shall be detected by the air ASE. 

3/ Definition of FISCancelContracts service parameters.

In section 2.4.4.2.1, the ASN.1 types "FISCancelContracts" and "FISCancelContractsAccept" are defined as a SEQUENCE OF "FISServiceType". 
This definition does not prohibit a redundancy of FISService Type nor does it limit the number of values to be mentionned (for example 'atis' could be mentionned 50 times).
This may affect the robustness of the ASE (as well as take up memory space).

Assigned SME:				Sub-Volume II SME

Proposed SARPs amendment: 

1/ Change 2.4.5.3.11.1 from:

c) create a FISDownlinkAPDU [FISCancelContractsAccept] APDU based on the value of the FISServiceType parameter, and

to:

c) create a FISUplinkAPDU [FISCancelContractsAccept] APDU based on the value of the FISServiceType parameter, and

2/ Change 2.4.5.3.10.2 from:

Upon receipt of [FISCancelContractsAccept] APDU, the CL module shall:

to:

Upon receipt of [FISCancelContractsAccept] APDU and the <<FISServiceType>> APDU-element matches exactly the <<FISServiceType>> APDU-element of the [FISCancelContracts] APDU sent previously, the CL module shall:

(<<xxx>> means that xxx is in italics)

3/ Change 2.4.4.2.1 from:

FISCancelContracts ::= SEQUENCE OF FISServiceType

FISCancelContractsAccept ::= SEQUENCE OF FISServiceType

FISServiceType ::= ENUMERATED
{
	-- Automatic Terminal Information Service (ATIS) Request
	atis (0),
	...
}

to:

FISCancelContracts ::= FISServiceType

FISCancelContractsAccept ::= FISServiceType

FISServiceType ::= BIT STRING
{
	-- Automatic Terminal Information Service (ATIS)
	atis (0)
} SIZE (1,...)


SME Recommendation to CCB:		RESOLVED

CCB Decision:				CCB-3: ACCEPTED
					CCB-4: RESOLVED (Montreal) 16/12/97