Mandatory fields

LISS fields are all optional unless otherwise specified. Consistent with our goal of making LISS simple, we have tried to make as few fields as possible mandatory.

Wherever an XmlRpc struct is used, each SIS and satellite system is free to add additional fields: any field that is not defined by this standard should be ignored by the receiving system, or interpreted at its own risk. (If a later version of LISS introduces new fields whose name overlap with customised fields’ names that a particular {SIS, satellite system} pair use, then it is the responsibility of those systems’ vendors to coordinate the change; Or they could choose a naming convention which guarantees that the field names will never clash with standard fields. Any fieldname containing a punctuation character is guaranteed never to be used by LISS).