Using Position
Add the fieldtype to your fieldset. You can choose to hide certain positions, by default they are all visible.
sections:
main:
display: Main
fields:
position:
type: position
options:
left: true
center: true
right: true
full: true
drop-left: true
drop-right: true
default: center
Using Position
The output of the fieldtype is equal to the keys in the options array.
{{ position }} // center