A single select list presents a set of options, from which one can be chosen. The screen below shows a series of select lists:
Clicking on the arrow next to Underlying Structures reveals the options for that field:
Only one option can be selected. Click on the option required to select it.
You can also close the list without changing the current setting by clicking on the arrow.
You will see a blank option among other options. If you select blank option for a list that previously had a value, it will delete the old value and set it to blank. You cannot select blank option for a required field. For details, see Validation Errors.
Notes and reports will not show old data in the note when you set it to blank.