Activity RefId xml:lang Title Preamble TechnicalRequirements TechnicalRequirement SoftwareRequirementList SoftwareRequirement SoftwareTitle Version Vendor OS EssentialMaterials EssentialMaterial LearningObjectives LearningObjective LearningStandards LearningStandardItemRefId SubjectArea Prerequisites Prerequisite Students StudentPersonalRefId SourceObjects SourceObject SIF_RefObject Points ActivityTime CreationDate Duration Units StartDate FinishDate DueDate AssessmentRefId MaxAttemptsAllowed ActivityWeight Evaluation EvaluationType Description LearningResources LearningResourceRefId SIF_Metadata SIF_ExtendedElements