RECOMMENDATIONS

These recommendations are primarily meant for the new versions of the packages under development or for those groups which are starting new developments of space VLBI user assistance software.

• The International Terrestrial Reference Frame and the International Celestial Reference Frame, maintained by the International Earth Rotation Service (IERS), should be adopted . If the applied frame is different for some reason, definition and transformation parameters should be specified in the user guide.
• The format and units of the parameter set should be standardized (i.e. station coordinates, source coordinates, orbital elements
• Time scales should be selectable by the user, but use YYMMDD and HHMMSS format and UTC as default.
• A menu driven interface should be the minimum requirement.
• Parameter files should be easy to edit and access. The elements of the parameter set should be easily modified and saved without going through too many steps.
• A common definition of the input and output formats should be adopted.
• With the exception of the RASTRON package, the other three packages don't have an accurate orbit prediction, which would take into account other effects than first order. It is recommended to investigate the long term predictability requirements and achievable accuracy and then implement the necessary orbit model.
• The latest orbital elements should be available for the users from the operating agencies via electronic access.
• All legal requirements should be stated very clearly and the rights of the user pertaining to the usage of the package..(Freely or not so freely redistributable, limited access to source code, no distribution of modified versions,etc..)