XML Specification for Navigation Data Messages - CCSDS

DRAFT XML SPECIFICATION FOR NAVIGATION DATA MESSAGES
4.13 USER DEFINED PARAMETERS
The ODM Version 2.0 introduced the notion of ‘user-defined parameters’. These parameters
are situation specific and not standardized, thus they must be specified in ICDs between the
exchange participants. The use of user-defined parameters is not encouraged. User-defined
parameters in the NDM/XML are only supported for the OMM and OPM Version 2; userdefined
parameters are not supported in the OEM Version 2 or any other Navigation Data
Message. Because these parameters are not known to the schema, there is only one very
broad keyword offered in the NDM/XML: . The user-defined
parameters appear in a logical block that is offset with the tag
. Following this tag, any number and order of
tags may appear. The KVN keywords for user-defined parameters are
formed by using the prefix ‘USER_DEFINED’ followed by a variable-length character string
that names the parameter. In the NDM/XML, the prefix shall be the XML tag and the
variable-length name of the parameter shall be the value for the ‘parameter’ attribute. All
information about the user-defined parameters shall be conveyed via the attributes
‘parameter’ and ‘value’. The type for ‘value’ shall be ‘xsd:string’, even if the value is
numeric.
For example, the following KVN parameters might appear in an OMM or OPM:
USER_DEFINED_ATMOSPHERE_MODEL = MSISE90
USER_DEFINED_C3 = 29.376
USER_DEFINED_EARTH_RADIUS = 6378.1
USER_DEFINED_3RD_BODY_PERTURBATION = JUPITER
These parameters would appear in an NDM/XML representation as:
MSISE90
29.376
6378.1
JUPITER
CCSDS 505.0-R-2 Page 4-25 June 2009