func (cm AsStandard) Convert() (*metadata.MSystem, error) {
	ms := &metadata.MSystem{}
	ms.Date = metadata.DateTime(cm.MSystem.Date)
	ms.Version = metadata.Version(cm.MSystem.Version)
	ms.System.ID = cm.MSystem.System.ID
	ms.System.Description = cm.MSystem.System.Description
	ms.System.MetadataID = cm.MSystem.System.MetadataID
	ms.System.TimeZoneOffset = cm.MSystem.System.TimeZoneOffset
	ms.System.Comments = cm.MSystem.Comments
	// TODO figure out how compact system sub-elements exists
	ms.System.MForeignKey = cm.MForeignKey()
	ms.System.MResource = cm.MResource()
	ms.System.MFilter = cm.MFilter()
	return ms, nil
}