Member cross-section symbols are used in the Structure task.
All section tables delivered with the software use a specific set of cross-section symbols. Some section tables use all the cross-section symbols in the set; some tables only use a subset of the cross-section symbols. Each cross-section symbol has its own set of properties. When looking at a section table workbook, you can determine the cross-section symbol that is being referenced by that particular sheet by looking at the SymbolDefinition entry at the top of the sheet.
The cross-section symbols are delivered with the reference data software in the [Reference Data Folder]\SharedContent\CrossSections folder. You can create your own custom cross-section symbols, sometimes referred to as arbitrary sections, using the 2D Symbols utility that is delivered with the software.
The software uses the simple physical representation of the cross-section symbol to display the member geometry in the model. You can change the display representation using the Selected Aspects option of Format Menu > View.
The delivered symbols contain a detailed physical representation. This representation is available only for marine models, and is not used for plant and materials handling models.
The delivered symbols also contain a production physical representation. This representation is available only for marine models in the Structural Manufacturing task, and is not used for plant and materials handling models.
See Cross-Section Symbol Representations in the 2D Symbols Help.