The documentation for versions 2.21 and older can be found here.
On this page
How many field types exist?
Currently, thirteen field types exist.
Those field types are:
Text input
Multiline text
Select
Multi select
Cascade select
Date input (old)
Date input (new)
User select
Phone number
Instant Messenger
Language select
Country select
Retrieved from LDAP
Dependent field
What are the benefits of the profile field type Select ?
The select field allows users to pick a single value out of a drop down menu.
Special configuration
In the section Field options, you can add options to the dropdown menu.
In the left field, enter the name of the option (for example: "Yes, I agree to be photographed.").
Then, click on the + button.
To re-order the options, click on the six dots button to the left of an option and re-position it via drag & drop. To delete an option, click on the deletebutton.