CCSDS 508.0-R-1, Conjunction Data Message (Red Book, Issue 1 ...

DRAFT CCSDS RECOMMENDED STANDARD FOR CONJUNCTION DATA MESSAGES6.3.2.5 In value fields that represent a time tag in UTC, values shall follow the conventionsof the ndm:epochType data type used in all CCSDS NDM/XML schemas.NOTE – An example of this format:yyyy-mm-ddThh:mm:ss[.d→d]where ‘yyyy’ is the year, ‘mm’ is the two-digit month, ‘dd’ is the two-digit dayof-monthseparated by hyphens, ‘T’ is a fixed separator between the date andtime portions of the string, and ‘hh:mm:ss[.d→d]’ is the time in hours, minutes,seconds and fractional seconds separated by colons. As many ‘d’ characters tothe right of the period as required may be used to obtain the required precision,up to the maximum allowed for a fixed-point number. Because all times in theCDM are UTC, the ‘Z’ indicator allowed by the CCSDS Time CodesRecommended Standard should be omitted. All fields require leading zeros (see6.2.2.11).6.3.2.6 In the value fields that represent TIME_LASTOB, the data type shall be either theexact time (see 6.3.2.5 for formatting rules) or an elapsed time, from the message creationtime, of the last observation used in the OD of the object. When the elapsed time option ischosen, the notation ‘LT’, ‘-’, and ‘GT’ shall be used.NOTE – The ‘LT’ means ‘less than’ as in ‘less than six hours’. The ‘-’ means ‘to’ as in ‘6-12’, meaning ‘six to twelve hours’. The ‘GT’ means ‘greater than’ as in ‘greaterthan twelve hours’.6.3.3 CDM UNITS IN XMLMany of the CDM tags must have a units attribute. In all cases, the units shall match thosespecified in table 3-2 and table 3-4 (including case).NOTE – Table 6-1 gives examples of XML keyword tags with specified units.Table 6-1: Example XML Keyword Tags with Specified UnitsTag Units ExampleMISS_DISTANCE m 715RELATIVE_SPEED m/s 14762ACTUAL_OD_SPAN d 5.50MAXIMUM_OBS_GAP h 2.36.3.4 CDM COMMENTS IN XMLComments are optional and must be displayed as values between the and tags, which may be in any case desired by the user.CCSDS 508.0-R-1 Page 6-6 March 2012