The High layer compatibility information element can be repeated in the SETUP message to indicate dual high layer capabilities for selection. By default, if the High layer compatibility information element is repeated without the Repeat indicator information element, it shall be interpreted as increasing order of priority.
NOTE - The High layer compatibility information element is transported transparently by an ISDN between a call originating entity, e.g. a calling user and the addressed entity, e.g. a remote user or a high layer function network node addressed by the call originating entity. However, if explicitly requested by the user (at subscription time), a network which provides some capabilities to realize teleservices may interpret this information to provide a particular service.
8 7 6 5 4 3 2 1
1 0 1 1 1 1 1 0 1 = 0x7D
2 length max 2+3
3 1 ext c c b b b a a
4 0/1 ext d d d d d d d
4.1 1 ext e e e e e e e
a) Presentation method of protocol profile (octet 3)
Bits
2 1
0 1 - High layer protocol profile (without specification of attributes)
All other values are reserved.
NOTE 4 - Currently, "Presentation method of protocol profile" has only
a single value, i.e. a "profile value" is used to indicate a service to be supported
by high layer protocols as required. Necessity of other presentation methods, e.g.
service
ions in the forum of layer-by-layer indication of protocols to be used
in high layers, is left for further study.
b) Interpretation (octet 3)
Bits
5 4 3
1 0 0 First (primary or only) high layer characteristics identification
(in octet 4) to be used in the call
All other values are reserved.
NOTE 2 - "Interpretation" indicates how the "High layer characteristics
identification" (in octet 4) should be interpreted.
NOTE 3 - Currently, "Interpretation" has only a single value. However,
"Interpretation", when enhanced, will be able to indicate how the "High layer
characteristics identification" in the same information element shall be
interpreted when multiple
layer characteristics identifications" are used and exact relationship among
them needs to be indicated (e.g. sequential usage, alternative list, simultaneous usage).
Such enhancements in conjunction with the possible negotiation procedures are left for
further study.
c) Coding standard (octet 3)
Bits
7 6
0 0 - CCITT standardized coding, as described below
0 1 - ISO/IEC standard (Note 1)
1 0 - National standard (Note 1)
1 1 - Standard defined for the network (either public or private) present
on the network side of the interface (Note 1)
NOTE 1 - These other coding standards should only be used only when the desired
high layer compatibility cannot be represented by CCITT standardized coding.
d) High layer characteristics identification (octet 4)
Bits
7 6 5 4 3 2 1
0 0 0 0 0 0 1 Telephony
0 0 0 0 1 0 0 Facsimile Group 2/3 (Recommendation F.182 [68])
0 1 0 0 0 0 1 Facsimile Group 4 Class I (Recommendation F.184 [69])
0 1 0 0 1 0 0 Teletex service, basic and mixed mode of operation (Recommendation F.230 [70]) and facsimile service Group 4, Classes II and III (Recommendation F.184)
0 1 0 1 0 0 0 Teletex service, basic and processable mode of operation (Recommendation F.220 [71])
0 1 1 0 0 0 1 Teletex service, basic mode of operation (Recommendation F.200 [72])
0 1 1 0 0 1 0 Syntax based Videotex (Recommendations F.300 [73] and T.102 [74])
0 1 1 0 0 1 1 International Videotex interworking via gateways or interworking units (Recommendations F.300 and T.101 [75])
0 1 1 0 1 0 1 Telex service (Recommendation F.60 [76])
0 1 1 1 0 0 0 Message Handling Systems (MHS) (X.400 - Series Recommendations [77])
1 0 0 0 0 0 1 OSI application (Note 2) (X.200 - Series Recommendations [78])
1 0 1 1 1 1 0 Reserved for maintenance (Note 4)
1 0 1 1 1 1 1 Reserved for management (Note 4)
1 1 0 0 0 0 0 Audio visual (Recommendation F.721 [79])
1 1 0 0 0 0 1
through Reserved for audiovisual services (F.700 - Recommandations Series [80])
1 1 0 1 1 1 1
1 1 1 1 1 1 1 Reserved
All other values are reserved.
NOTES
1 The coding above applies in case of "Coding standard" = "CCITT standard" and "Presentation method of protocol profile" = "High layer protocol profile".
2 Further compatibility checking will be executed by the OSI high layer protocol.
3 Code points are added only to those services for which CCITT Recommendations are available. See also Recommendation I.241 [34].
4 When this coding is included, octet 4 may be followed by octet 4a.
e) Extended high layer characteristics identification (octet 4a)
Bits
7 6 5 4 3 2 1
0 0 0 0 0 0 1 Telephony
0 0 0 0 1 0 0 Facsimile Group 2/3 (Recommendation F.182)
0 1 0 0 0 0 1 Facsimile Group 4 Class I (Recommendation F.184)
0 1 0 0 1 0 0 Teletex service, basic and mixed mode of operation (Recommendation F.230) and facsimile service Group 4, Classes II and III (Recommendation F.184)
0 1 0 1 0 0 0 Teletex service, basic and processable mode of operation (Recommendation F.220)
0 1 1 0 0 0 1 Teletex service, basic mode of operation (Recommendation F.200)
0 1 1 0 0 1 0 Syntax based Videotex (Recommendations F.300 and T.102)
0 1 1 0 0 1 1 International Videotex interworking via gateways or interworking units (Recommendations F.300 and T.101)
0 1 1 0 1 0 1 Telex service (Recommendation F.60)
0 1 1 1 0 0 0 Message Handling Systems (MHS) (X.400 - Series Recommendations)
1 0 0 0 0 0 1 OSI application (Note 2) (X.200 - Series Recommendations)
1 0 1 1 1 1 0 Not available for assignment
1 0 1 1 1 1 1 Not available for assignment
1 1 0 0 0 0 0 Audio visual (Recommendation F.721)
1 1 0 0 0 0 1
through Reserved for audiovisual services (F.700 - Series Recommendations)
1 1 0 1 1 1 1
1 1 1 1 1 1 1 Reserved
All other values are reserved.