A-1) The number of characters in the surveillance equipment and capabilities subset of Item 10 has been defined as a maximum of 20 characters. However other subsets in Item 10 have not had ‘maximum characters’ defined, nor had many of the other fields. Recognizing that a defined number of characters per field or sub field was valuable when coding software as it removed any need to make field capacity available that would never be used, the meeting sought clarification as to the different approach applied to different fields. The meeting also considered that agreeing on an Asia/Pacific requirement for number of characters per field or sub field would result in worthwhile standardisation and economies for States and should be pursued by the Task Force and adopted as a regional flight planning constraint.

The limitation of 20 characters for the surveillance equipment and capabilities of Item 10 was considered appropriate taking into consideration the number of possible entries. For the navigation/communication equipment and capabilities, it was recommended not to establish a limit due to the number of possible combinations.  The creation of a regional “sub-specification”, while beneficial for intra-regional operations, may pose significant impact on inter-regional operations by raising both the complexity and potential for the establishment of regional standards that, in the aggregate, may exceed the overall message length limitations. Considering the above, it is recommended to keep the size of Item 10 for the NAV/COM with the capacity to inform the recipient of as many equipment and capabilities as possible, and to balance this with the message total length.